View source for St. Louis County, Missouri

{{short description|County in Missouri, United States}}
{{distinguish|text=[[St. Louis County, Minnesota]] or the [[Independent city (United States)|independent city]] of [[St. Louis]]}}
{{Use American English|date=June 2025}}
{{Use mdy dates|date=April 2024}}
{{Infobox U.S. county
| <!-- Infobox uses county name for the map so use 'Saint' not 'St.' so the map shows [:File:Map of Missouri highlighting Saint Louis County.svg] -->
 | county             = Saint Louis County
 | state              = Missouri
 | ex image           = MetroLink Blue Line in Clayton.jpg
 | ex image size      = 300px
 | ex image cap       = Clayton, the St. Louis County seat
 | type               = [[County (United States)|County]]
 | flag               = flag of St. Louis County, Missouri (2025).jpg
 | seal               = Seal of St. Louis County, Missouri.svg
 | logo               = The_logo_of_St._Louis_County.jpeg
 | coordinates        = {{Coord|38|38|26.477|N|90|26|45.862|W|region:US-MO_type:county|display=inline}}
 | founded year       = 1812
 | founded date       = October 1
 | named for          = 
 | seat wl            = Clayton
 | largest city wl    = Florissant
 | leader_title       = County executive
 | leader_name        = [[Sam Page (politician)|Sam Page]] ([[Democratic Party (United States)|D]])
 | area_total_sq_mi   = 523.366
 | area_land_sq_mi    = 507.995
 | area_water_sq_mi   = 15.371
 | area percentage    = 2.9%
 | population_total   = 1004125
 | population_as_of   = 2020
 | population_est     = 987059 {{decrease}}
 | pop_est_as_of      = 2023
 | density_sq_mi      = 1943.527
 | time zone          = Central
 | district           = 1st
 | district2          = 2nd
 | website            = {{URL|https://stlouiscountymo.gov/|stlouiscountymo.gov}}
}}

'''St. Louis County''' is located in eastern [[Missouri]]. It is bounded by the [[St. Louis|City of St. Louis]] and the [[Mississippi River]] to the east, the [[Missouri River]] to the north, and the [[Meramec River]] to the south. As of the [[2020 United States census|2020 census]], the population was 1,004,125,<ref name="2020 Census (City)">{{cite web|title=Explore Census Data |url=https://data.census.gov/profile/St._Louis_County,_Missouri?g=050XX00US29189 |publisher=[[United States Census Bureau]] |access-date=February 17, 2025}}</ref> making it the [[List of counties in Missouri|most populous county in Missouri]], and was estimated to be 987,059 in 2023.<ref name="QF"/> Its [[county seat]] is [[Clayton, Missouri|Clayton]].<ref name="GR6">{{cite web|url=http://www.naco.org/Counties/Pages/FindACounty.aspx|access-date=June 7, 2011|title=Find a County|publisher=National Association of Counties}}</ref> The county is included in the [[Greater St. Louis|St. Louis, MO–IL]] metropolitan statistical area.

After Great Britain took over former French territory east of the Mississippi River, many ethnic French colonists moved west. They settled the area of St. Louis County and founded the city of St. Louis in the late 1700s. The US acquired this territory in 1803 with the [[Louisiana Purchase]].

In 1877 residents of the City of St. Louis voted to separate from the county and become an [[Independent city (United States)|independent city]]. In the 1960s, with growing suburban development of [[Greater St. Louis]], the county's population overtook that of the city for the first time. Restructuring of industry resulted in job and population declines in the city, and the county has continued to expand.

Through the decades changing conditions have led many business and political leaders to propose [[Consolidated city-county|merging the city and county as a single government]]. In 2019, efforts to put the issue to a statewide vote failed to get on a ballot.<ref>{{Cite news|url=https://www.stltoday.com/news/local/govt-and-politics/metro-city-better-together-launches-a-two-year-effort-to/article_c2f6dca1-c450-5aba-b837-9802da767f88.html|title='Metro City': Better Together launches a two-year effort to meld St. Louis city and county|first1=Jeremy |last1=Kohler |first2=David |last2=Hunn|newspaper=St. Louis Post-Dispatch |date=January 29, 2019 |access-date=May 24, 2024}}</ref>

==History==

===Colonial settlement and early government===
{{see also|History of St. Louis}}
During the 18th century, several European colonial settlements were established in the area that would become St. Louis County. French colonists moved from east of the Mississippi River after France ceded territory to Great Britain after losing the Seven Years' War. It also ceded much of its territory west of the River to Spain.

St. Louis was founded by [[Pierre Laclède]] and [[Auguste Chouteau]] on February 14, 1764; they became major fur traders in the city.<ref name="cohn26">Cohn, 26.</ref> Founded in about 1767 was [[Carondelet, St. Louis|Carondelet]], to the south. It was annexed by the city in 1871.<ref name="cohn26"/> [[Florissant, Missouri|Florissant]], then known as St. Ferdinand, was established in 1785 about twelve miles northwest of St. Louis on a tributary of the [[Missouri River]].<ref name="cohn26"/> During the 1790s, the very small settlements known as [[Creve Coeur, Missouri|Creve Coeur]] and Point Labadie were built north and west of St. Louis.<ref name="cohn26"/>

Upon the sale and transfer of [[Louisiana (New France)|French Louisiana]] to the United States on October 1, 1804, President [[Thomas Jefferson]] suggested the territory retain the districts drawn by Spanish officials during their decades-long rule of the territory after an arrangement with the French.<ref name="cohn25">Cohn, 25.</ref> During this time, the first governing body of St. Louis County was established (following the earlier Spanish governors).<ref name="cohn27">Cohn, 27.</ref>

This government, called the Court of Quarter Sessions, was composed of [[Charles Gratiot]], Auguste Chouteau, [[Jacques Clamorgan]], and [[David DeLaunay]], all ethnic French or French Canadians; the court held judicial, executive, and legislative power.<ref name="cohn27"/> On October 1, 1812, the District of St. Louis was renamed St. Louis County (exactly eight years after its establishment) during a federal reorganization of the Louisiana Territory's status.<ref name="cohn25"/>

===Antebellum growth and early education===
After the transfer of Louisiana to the United States, the authority to grant incorporation to municipalities was delegated to the Territory and later was a state power.<ref name="cohn58">Cohn, 58.</ref> The first to gain municipal status in St. Louis County was St. Louis, which incorporated on November 9, 1809, under the territorial legislature. It gained city status on December 9, 1822.<ref name="cohn26"/> Only a handful of other municipal incorporations took place prior to the separation of the county and city: St. Ferdinand was granted incorporation in 1829 (and reincorporated as Florissant in 1843), while [[Bridgeton, Missouri|Bridgeton]], a settlement along the Missouri River near Florissant, gained incorporation in 1843.<ref name="cohn58"/>

The towns of [[Pacific, Missouri|Pacific]] and [[Kirkwood, Missouri|Kirkwood]] grew substantially and incorporated in the 1850s, with their growth stimulated by construction of the [[Pacific Railroad]] (later the [[Missouri Pacific Railroad]]).<ref name="cohn58"/> Pacific, a community along the [[Meramec River]] first known as Franklin, straddles St. Louis and Franklin counties; it incorporated as Pacific in 1859.<ref name="cohn58"/> Kirkwood was settled in 1853 after Hiram Leffingwell and Richard Elliott platted and auctioned land along the railroad line; they named their settlement after [[James P. Kirkwood]], who had planned the route of the railroad through the area.<ref name="bergererwin7">Berger Erwin, 7.</ref> Leffingwell organized the town as a planned suburb (the first west of the Mississippi). Kirkwood was granted incorporation by the state in 1865.<ref name="cohn58"/><ref name="bergererwin7"/>

Other areas of the county began to be settled during this period but did not incorporate as towns.<ref name="cohn63">Cohn, 63.</ref> Among these were [[Chesterfield, Missouri|Chesterfield]], which was settled in the 1820s in west St. Louis County. Gravois and [[Affton, Missouri|Affton]] were settled in south St. Louis County in the 1850s and 1860s.<ref name="cohn63"/>

The first [[St. Louis Public Schools]] were established in the major city in the 1830s. It was a decade and more before some of the settlements of St. Louis County began providing public education.<ref name="thomas 67">Thomas, 67.</ref> In 1854, the [[Maplewood-Richmond Heights School District|School District of Maplewood]] was established. It included all of today's Maplewood district, part of what became [[Webster Groves, Missouri]], along the south and southwest, a large part of St. Louis in the east, and to the north up to Clayton Road.<ref name="thomas 67" /> The first school, originally called the Washington Institute and later renamed as Maplewood High School, opened as a one-room stone building at the crossing of Manchester Road over the Missouri Pacific Railroad tracks.<ref name="thomas 67" /> Another [[Antebellum South|antebellum]] school district was Rock Hill, which provided a one-room school across from the Rock Hill Presbyterian Church until about 1870.<ref name="thomas122">Thomas, 122.</ref>

The first school in Florissant opened in 1819 under the direction of the [[Society of the Sacred Heart|Religious of the Sacred Heart]], a Roman Catholic religious congregation.<ref name="davison61">Davison, 61.</ref> The instructor, [[Rose Philippine Duchesne]], was a French immigrant who has been described as "one of the foremost educators in the state of Missouri".<ref name="davison61"/> A second school, initially an Indian school known as the St. Regis Academy, was operated for young boys from 1823 to 1829. The complex included the Jesuit [[St. Stanislaus Seminary]], which continued to operate until 1971.<ref name="davison63">Davison, 63.</ref> The earliest public school in Florissant was the St. Ferdinand School, which was authorized by the General Assembly in 1845 and operated until 1871 when the Florissant School District was formed.<ref name="davison67">Davison, 67.</ref>

===Government changes and early courthouses===
From 1813 to 1830, the county initiated several changes to its government. By an act of the territorial legislature, the Court of Quarter Sessions was succeeded by a panel of three judges of common pleas in 1813.<ref name="cohn27"/> Two years later, this panel was succeeded by a newly created county court in 1815, composed of justices of the peace elected from the county to three-month terms.<ref name="cohn27"/> The St. Louis County Circuit Court (established in 1815 as the judicial branch of the county) was given authority in 1816 over the executive and legislative affairs of the county, superseding the court of justices of the peace.<ref name="cohn27"/>

In 1821, a hybrid County and Probate Court was established and given executive and legislative control, and in 1830, its probate functions ceased.<ref name="cohn27"/> This County Court operated as the government of St. Louis County until public scandals encouraged the state legislature to abolish it and replace it in 1859 with a [[County commission|Board of Commissioners]].<ref name="cohn27"/>

[[File:The Old Courthouse, Saint Louis, Missouri.JPG|thumb|left|The [[Old Courthouse (St. Louis)|Old Courthouse]] was built in downtown St. Louis from 1839 to 1856 as the second purpose-built county courthouse for St. Louis County.]]
Sessions of the County Court and other county governing bodies were held in a variety of locations during this early period.<ref name="cohn36">Cohn, 36.</ref> The Court of Quarter Sessions held its first meeting in 1804 at a tavern in St. Louis, then regularly at a building at Third and Plum until 1817.<ref name="cohn36"/> The county seat moved that year to a newly built one-story log cabin on Third Street between Elm and Spruce, followed by a move to the brick Baptist Church at Third and Market in 1820.<ref name="cohn36"/>

The County Court established a commission in 1822 to study a permanent courthouse (previous facilities were rented). In 1823, Auguste Chouteau and [[John Baptiste Charles Lucas]] donated two tracts of land that formed a vacant square bounded by Broadway, Fourth, Chestnut, and Market.<ref name="cohn36"/>

Between the summer of 1826 and 1833, a low-roofed two-story brick structure was built fronting Fourth Street; this was the first permanent courthouse for St. Louis County.<ref name="cohn36"/> Within a few years, however, the building's size was inadequate for the county government's needs; the original building was left in place during construction on the new building, which began in 1839.<ref name="cohn36"/> This new courthouse, now known as the [[Old Courthouse (St. Louis)|Old Courthouse]], included a finished rotunda, dome, and west wing by 1843; the 1833 courthouse was demolished in 1851, and by 1856, the east wing of the new courthouse was complete.<ref name="cohn36"/>

===Separation of St. Louis and St. Louis County===
During the antebellum period, some city leaders began to work to separate the city of St. Louis, the county's largest municipality, from the county.<ref name="cohn27"/> In 1843, a group of St. Louis city residents petitioned the state legislature to separate the two entities. The General Assembly passed a resolution calling for a referendum on the subject among county voters outside the city.<ref name="cohn27"/> This vote held on August 7, 1844, showed a majority of county voters opposed to separation.<ref name="cohn27"/>

Despite the vote, controversy continued and tension mounted between the county government and the city government during the 1840s and 1850s.<ref name="cohn27"/><ref name="cassella">William N. Cassella, Jr. "City-County Separation: The Great Divorce of 1876." ''Missouri Historical Society Bulletin.'' (January 1959).</ref> Much of the dispute involved the double taxation of city residents and their proportionally lesser representation in county government.<ref name="cohn28">Cohn, 28.</ref> The reform of 1859, in which the County Court was abolished by the state government and replaced by a Board of Commissioners, was in large part a reaction to city outcry over mismanagement of tax money.<ref name="cohn28"/> More than a name change, the reform expanded the size of the county government council to seven members, with four seats reserved for city representation (but the city at that time had roughly ten times the population of the county, so was still underrepresented in county government).<ref name="cohn28"/> The reform temporarily ameliorated the tensions. In 1863, the General Assembly restored the name of the county government to its former name of County Court.<ref name="cohn28"/>

Despite some reforms, controversy returned and grew during the 1860s. This was largely due to what city residents considered double taxation: by the county and the city for services effectively provided by the city alone.<ref name="cohn28"/> Several plans began to circulate during the late 1860s that would relieve this burden, including home rule status for St. Louis, further reorganization of the County Court to ensure greater representation, city-county government consolidation, and separation of the two entities.<ref name="cohn28"/> The General Assembly considered several plans during this period. In March 1871, it passed a further reorganization of the County Court; the new Court would have an presiding judge elected [[at-large]], four seats reserved to be elected by city residents, and two seats for county residents.<ref name="cohn29">Cohn, 29.</ref> This reform, however, pleased virtually no one pushing for reform, and it made little practical difference in the operation of the county government.<ref name="cohn29"/>

[[File:David H. Armstrong - Brady-Handy.jpg|thumb|right|Local politician [[David H. Armstrong]] was a strong supporter of the separation of the city of St. Louis from St. Louis County.]]
A consolidation plan proceeded in the General Assembly in 1871, backed by city political leaders [[Anthony Ittner]] and [[Roderick E. Rombauer]].<ref name="cohn29"/> The ''[[Missouri Republican]]'' newspaper strongly backed the approach, while the ''[[St. Louis Globe-Democrat|Missouri Democrat]]'' argued it would lead city leaders into corruption.<ref name="cohn29"/> The latter pressed for a separation plan, support for which was led by [[David H. Armstrong]].<ref name="cohn29"/> The separation plan gained greater support when it became clear that the mistrust between city and county residents precluded consolidation.<ref name="cohn29"/> A citizen group known as the Taxpayers League formed in 1872 to advance the separation cause. City leaders looked to [[Baltimore]], [[Maryland]], which had separated from Baltimore County in 1853, as an example.<ref name="cohn29"/>

The mechanism by which separation took place began in 1875 at the state constitutional convention.<ref name="cohn29"/> At the convention, a committee examined the issues of the St. Louis government, and it summarized the two options facing the region as consolidation and separation.<ref name="cohn29"/> The full convention voted to include a provision in the constitution allowing for separation; the vote was 53 in favor, 4 opposed, 11 absent.<ref name="cohn29"/> Only one member of the St. Louis delegation opposed separation:

{{blockquote|I am in favor of total consolidation of St. Louis County, but I am not in favor of dividing it, splitting and hacking it in this manner...I vote no.|Nicolas A. Mortell|Cohn, 29.}}

In 1877, the [[St. Louis|City of St. Louis]] separated from the county, creating an [[Independent city (United States)|independent city]]. The city in August 1876 narrowly approved the separation while county residents overwhelmingly opposed the separation. City residents had argued they wanted to be "rid of county taxes and state influence over county government". At the time the city had 350,000 residents while the rural county had 30,000. The rural county also had only 150 miles of gravel roads. Although the results were challenged in the courts, the two jurisdictions were formally separated in March 1877.<ref name="stltoday1">{{cite web|first=Tim |last=O'Neil |url=http://www.stltoday.com/news/local/metro/article_a7f6b2d1-a7f6-522c-800b-043ef04bd23a.html |title=A Look Back: Ralph Clayton gave land for county seat |newspaper=St. Louis Post-Dispatch |date=April 17, 2011 |access-date=May 24, 2024 |archive-url=https://web.archive.org/web/20110418093229/http://www.stltoday.com/news/local/metro/article_a7f6b2d1-a7f6-522c-800b-043ef04bd23a.html |archive-date=April 18, 2011 |url-status=dead}}</ref>

===Postseparation political issues===
The first meeting of the new County Court took place on January 22, 1877, at the home of James C. Sutton, in what is now [[Maplewood, Missouri|Maplewood]]. The three judges appointed a new county clerk, sheriff, and treasurer.<ref name="cohn33">Cohn, 33.</ref> They also announced at that meeting that the new Court was functional (obviating the legal standing of the previous County Court, which continued to meet albeit without legal function until July 1877) and the transfer of all county buildings and property in the city of St. Louis to the city government.<ref name="cohn33"/> Thus the county's courthouse in St. Louis became city property. The Court also requested that the city of St. Louis continue to provide police protection to some areas of the county until the county could provide these services.<ref name="cohn33"/>

On January 29, 1877, the Court considered a report that recommended Kirkwood as the new county seat, but did not decide the issue at that time.<ref name="cohn34">Cohn, 34.</ref> The Court continued to meet at the Sutton House in Maplewood until February 1877, when it convened at the Des Peres Grange Hall. It agreed then to rent space at the Mount Olive Hotel, in what is now [[University City, Missouri|University City]], until deciding on a new location for the courthouse.<ref name="cohn35">Cohn, 35.</ref> The Court continued to meet at the Mount Olive Hotel from March 1877 to 1879.<ref name="cohn35"/> Throughout 1877, the Court debated the question of the county seat; rejecting several sites, including Kirkwood and Florissant.<ref name="cohn35"/>

In September 1877 the Court accepted the donation of 100 acres of land on Hanley Road by a farmer named Ralph Clayton.<ref name="cohn35"/> In addition to the benefit of donated land, the site was chosen because it was on the route of the [[Streetcars in St. Louis|Hodiamont streetcar line]], which connected from St. Louis to Florissant.<ref>{{cite web |url=http://ww5.stlouisco.com/parks/History1.html |title=St Louis County Parks and Recreation |publisher=Ww5.stlouisco.com |access-date=April 26, 2011}}{{dead link|date=March 2018 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> An additional four acres were given by M. F. Hanley,<ref name="cohn35"/> and in May 1878, the cornerstone was laid for a new county courthouse.<ref name="cohn37">Cohn, 37.</ref> In October 1878 the courthouse donation and streets were platted in what would become the town of [[Clayton, Missouri|Clayton]].<ref name="cohn35"/> The new courthouse and jail opened in December 1878, at a cost of $38,000.<ref name="cohn37"/> Two additions were made to the courthouse in 1912 and in 1926.<ref name="cohn37"/>

===Growth of education and municipalities===
In the years from the Civil War to World War I, relatively few new towns incorporated in St. Louis County; the first to incorporate after the war, [[Fenton, Missouri|Fenton]], was incorporated in 1874 in southwest St. Louis County.<ref name="cohn110-112">Cohn, 110-112.</ref> [[Webster Groves, Missouri|Webster Groves]] incorporated in 1896, prompted by residents' demands for a police department after the murder of Bertram Atwater, a commercial artist from Chicago.<ref name="hemphill10">Hemphill, 10.</ref> Webster had earlier been settled in 1853 as a stop on the Missouri Pacific line.<ref name="hemphill8">Hemphill, 8.</ref>

Other incorporations before World War I included University City in 1906 near [[Washington University in St. Louis]]; Maplewood in 1908, also along the Missouri Pacific railroad line; [[Wellston, Missouri|Wellston]] in 1908 in the inner north county; [[Shrewsbury, Missouri|Shrewsbury]] in 1913 east  of Webster Groves; Clayton in 1913 south of University City; and [[Richmond Heights, Missouri|Richmond Heights]] in 1913 south of Clayton.<ref name="cohn110-112"/> State law required only that 50% of residents agree to incorporation via a petition for a legal incorporation to take place; the county government had no ability to restrict the incorporation if the 50% threshold were met.<ref name="cohn58"/> Significant suburban growth in the early 20th century stimulated a rapid increase in the number of incorporations after 1935.

After the Civil War, dozens of school districts opened in St. Louis County to provide basic primary education. In [[Eureka, Missouri|Eureka]], along the Missouri Pacific line to Pacific, a one-room log school opened in the town in 1870, which expanded to two stories and four rooms in about 1900.<ref name="beck41">Beck, 41.</ref> In the towns of Old Orchard and Webster Groves along the Missouri Pacific line, schools opened in 1867 and 1868, respectively.<ref name="hemphill8"/> In Kirkwood, private schools began operating within a few years of the first settlers purchasing lots in 1853; in the early 1860s, these included the Kirkwood Seminary (which closed in 1889), the Kirkwood Military Academy, St. Peter Catholic School, and Concordia Lutheran School.<ref name="bergererwin8">Berger Erwin, 8.</ref> The first public schools in Kirkwood opened in 1866 as part of the newly formed [[Kirkwood School District]]; the district provided two years of high school from 1873 and opened a four-year [[Kirkwood High School]] in 1896.<ref name="bergererwin8"/>

In some areas, formerly private schools became part of new public districts. In Florissant, the St. Ferdinand School (opened in 1845) became part of the [[Ferguson-Florissant School District|Florissant School District]] in 1871, although it continued to be staffed by nuns. The first public school in the newly formed district opened in 1876 near St. Ferdinand and Washington Streets.<ref name="davison67"/> In [[Ballwin, Missouri|Ballwin]], a school opened in 1855 by German Methodists was bought by a newly formed Ballwin School District in 1869. The one-room schoolhouse operated until 1900 when a two-room building opened as a replacement.<ref name="fiedler91">Fiedler, 91.</ref>

===Postwar===
A new courthouse was built in Clayton in 1945 (it serves as the 21st-century County Police headquarters). The original 1878 courthouse was torn down in 1971 to be replaced by county government plaza and modern six-story courthouse.<ref name="stltoday1"/>

Several changes took place in St. Louis County education after World War II. The Florissant School District and the Ferguson School District merged in October 1951 to form the Ferguson-Florissant School District.<ref name="davison68">Davison, 68.</ref> As part of a court-ordered desegregation plan, in 1975 the Ferguson-Florissant district annexed the Kinloch and the Berkeley school districts to combine the schools.<ref name="davison68"/>

In 1955, St. Louis County established the [[St. Louis County Police Department]], with jurisdiction throughout the county. In 1977, St. Louis County was terrorized by [[South County car bomber|three car bombings]], which killed two people. The bomber was never caught.

In 1988 the Board of Freeholders proposed consolidating the county's 89 municipalities into 37 cities, eliminating all unincorporated areas. The vote in June 1989 was challenged by numerous groups on grounds questioning the board's constitutional authority. On June 25, days after the scheduled vote would have occurred, the U.S. Supreme Court unanimously overturned the [[Missouri Supreme Court]], arguing the board's land ownership requirement violated the U.S. Constitution's [[Equal Protection Clause]].<ref>{{cite book|last1=Tranel|first1=Mark|title=St. Louis Plans: The Ideal and the Real St. Louis|date=2007|publisher=Missouri History Museum|pages=70–74|isbn=9781883982614|url=https://books.google.com/books?id=vvrdp7Kn3kgC|access-date=June 19, 2017}}</ref>

The county passed the city in population in the [[1970 United States census|1970 census]] when it had 951,353 compared to the city's 622,236. Industrial restructuring cost the city many jobs and residents. By the [[2010 United States census|2010 census]], the city had fewer people than in the 19th century.

==Geography==
According to the [[United States Census Bureau]], the county has a total area of {{convert|523.366|sqmi}}, of which {{convert|507.995|sqmi}} is land and {{convert|15.371|sqmi}} (2.9%) is water.<ref>{{Cite web|title=2024 County Gazetteer Files – Missouri|url=https://www2.census.gov/geo/docs/maps-data/data/gazetteer/2024_Gazetteer/2024_gaz_counties_29.txt|publisher=[[United States Census Bureau]]|access-date=February 17, 2025}}</ref>

Colloquially, St. Louis County is often divided into Mid, North, West, and South sections. North County lies north of [[Interstate 70 in Missouri|Interstate 70]], West County lies west of [[Interstate 270 (Missouri–Illinois)|Interstate 270]], South County lies south of [[Interstate 44]] and Mid County lies in the middle of the three main bordering highways (I-70, I-270 & I-44) and the St. Louis county-city line.{{citation needed|date=August 2018}}

===Natural boundaries===
The [[Missouri River]] forms the northern border with [[St. Charles County, Missouri|St. Charles County]], exclusive of a few areas where the river has changed its course. The [[Meramec River]] forms most of its southern border with [[Jefferson County, Missouri|Jefferson County]]. To the east is the City of [[St. Louis]] and the [[Mississippi River]]. The western boundary with [[Franklin County, Missouri|Franklin County]] is the north–south line where the distance between the Meramec and Missouri rivers is the shortest, bisecting the city of [[Pacific, Missouri|Pacific]], roughly two blocks east of Hwy OO/F (First street).

===Topography===
The foothills of the Ozark Mountains begin in southwestern St. Louis County, with most of the rest of the county being a fairly level plateau. This western part of the county is the least developed, due to rugged topography. Bluffs along the Mississippi in the south of the county rise about 200–300 feet above the river. A major floodplain area is the [[Chesterfield, Missouri|Chesterfield Valley]], in the western part of the county, along the Missouri River. It was formerly called "Gumbo Flats" after its rich, dark soil; it was submerged by at least ten feet of water during the [[Great Flood of 1993]]. The Corps of Engineers constructed a higher levee, and the county has permitted construction in the floodplain.

The Columbia Bottom is a floodplain in the northeast of the county at the [[confluence]] of the Mississippi and Missouri rivers; this is preserved as a conservation area open to the public. The Missouri Bottom area between the two other floodplains had been developed for agriculture, but it is being increasingly developed for residential, business, and industry. The [[River des Peres]] drains the interior of the county before flowing into constructed underground channels into the City of St. Louis. It was allowed to resurface, where it forms the boundary between southern portions of St. Louis City and St. Louis County. Other streams include [[Coldwater Creek (Missouri river tributary)|Coldwater Creek]], [[Bonhomme Creek]], and Creve Coeur Creek, flowing into the [[Missouri River]]; [[Keifer Creek]], Fishpot Creek, and Grand Glaize Creek, flowing into the [[Meramec River]]; Deer Creek and [[Gravois Creek]], flowing into the [[River des Peres]]; and [[Maline Creek]], flowing into the [[Mississippi River]]. The highest elevation is {{convert|904|ft|m|abbr=off|sp=us}}.<ref>USGS 1/3 Arc Second NED</ref>

===Geology===
The bedrock is mainly [[limestone]] and [[Dolomite (rock)|dolomite]], and much of the county near the rivers is [[karst]] terrain, with numerous caves, sinkholes, and springs. No [[Igneous rock|igneous]] or [[metamorphic rock]] is exposed on the surface. A major outcropping of the [[St. Peter Sandstone]] formation, a fine white sandstone used for making clear glass, is mined in the southwest corner of the county in [[Pacific, Missouri|Pacific]]. Brick clay mining was once a major industry in the county. The Charbonier Bluff along the Missouri River is an outcropping of coal and was used a fueling station for [[steamboat]]s. The "St. Louis Anticline", an underground formation, has small petroleum deposits in the north part of the county.

===Flora and fauna===
Before European settlement, the area was prairie and open parklike forest, maintained by [[Native Americans in the United States|Native Americans]] via burning. Trees are mainly [[oak]], [[maple]], and [[hickory]], similar to the forests of the [[Ozarks]]; common understory trees include [[Cercis canadensis|eastern redbud]], [[Amelanchier|serviceberry]], and [[Cornus florida|flowering dogwood]]. [[Riparian]] areas are heavily forested with mainly [[American sycamore]]. By the 1920s most of the timber in the county was harvested. Since that time, large parks and undeveloped areas in the western and southern parts of the county have grown dense forest cover. Old pastures are usually colonized with [[Juniperus virginiana|eastern red cedar]]. Most of the residential area of the county is planted with large native shade trees. In autumn, the changing color of the trees is notable. St. Louis County has the most recorded native species of plants in the state, but this is probably due to the intensive botanical research done in the area. Most species here are typical of the Eastern Woodland, but some southern species are found in swampland, and typical northern species survive in sheltered [[Valley|hollows]]. Invasive species, most notably [[Lonicera japonica|Japanese honeysuckle]], are common in some homesteads converted to parks; these are actively removed.

Large [[mammal]]s include growing populations of [[White-tailed deer|whitetail deer]] and [[coyote]]s, which are becoming increasingly urbanized. [[Eastern gray squirrel]], [[cottontail rabbit]], and other rodents are abundant, as well as [[opossum]], [[beaver]], [[muskrat]], [[raccoon]], and [[skunk]]. Large bird species include [[wild turkey]], [[Canada goose]], [[mallard duck]], various [[bird of prey|raptors]] like the [[turkey vulture]] and [[red-tailed hawk]], as well as [[Wader|shorebirds]], including the [[great egret]] and [[great blue heron]]. Winter populations of [[bald eagle]]s are found by the [[Mississippi River]] around the [[Chain of Rocks Bridge]]. The county is on the [[Mississippi Flyway]], used by migrating birds, and has a large variety of small bird species, common to the eastern U.S. The [[Eurasian tree sparrow]], an introduced species, is limited in North America to the counties surrounding St. Louis.

Frogs are commonly found in the springtime, especially after extensive wet periods. Common species include [[American toad]] and species of chorus frogs, commonly called "[[spring peeper]]s", that are found in nearly every pond. Some years have outbreaks of [[cicada]]s or [[ladybugs]]. [[Mosquito]]s and [[Housefly|houseflies]] are common [[insect]] nuisances; because of this, windows are nearly universally fitted with [[Window screen|screens]], and "screened-in" [[porch]]es are common in homes of the area. Populations of [[Western honey bee|honeybees]] have sharply declined in recent years, and numerous species of [[Pollination|pollinator]] insects have filled their ecological niche.

===Climate===
{{climate chart
|  St. Louis County
| -8| 4| 66
| -4| 7| 75
| 4| 17| 85
| 10| 24| 204
| 15| 26| 108
| 20| 37| 128
| 22| 31| 47
| 20| 31| 113
| 17| 29| 97
| 10| 21| 90
| 4| 15| 46
| -5| 5| 81
|float=right
|clear=both
|source = <ref name = "nasa">{{Cite web|url= http://neo.sci.gsfc.nasa.gov/dataset_index.php|title= NASA Earth Observations Data Set Index|access-date=January 30, 2016|publisher= NASA|archive-date= April 7, 2019|archive-url= https://web.archive.org/web/20190407091601/https://neo.sci.gsfc.nasa.gov/dataset_index.php|url-status= dead}}</ref>
}}
St. Louis County has a mix of a humid subtropical climate and a humid continental climate, with neither large mountains nor large bodies of water to moderate its temperature. The area is affected by both cold Canadian Arctic air, and also hot, humid air from the [[Gulf of Mexico]]. The county has four distinct seasons. Spring is the wettest season and produces erratic severe weather ranging from [[tornado]]es to [[winter storm]]s. Summers are hot, and the humidity can cause the [[heat index]] to rise to temperatures above {{convert|100|F}}. Fall is mild, with lower humidity and can produce intermittent bouts of heavy rainfall with the first [[snow flurry|snow flurries]] usually forming in late November. Winters are cool to cold with periodic snow and temperatures often below freezing. Winter storm systems, such as [[Alberta clipper]]s, can bring days of heavy [[freezing rain]], [[ice pellets]], and [[snow]]fall.

The average annual temperature for the years 1971–2000, recorded at [[Lambert–St. Louis International Airport]], is {{convert|56.3|F}}, and average precipitation is {{convert|36|in}}. The average high temperature in July is {{convert|88.4|F}}, and the average low temperature in January is {{convert|22.6|F}}, although these values are often exceeded. Temperatures of {{convert|0|F}} or below occur three days per year on average.<ref>[http://www.weatherexplained.com/Vol-4/2001-St-Louis-Missouri-STL.html 2001 ST. LOUIS, MISSOURI (STL)]. Weather Explained, Volume 4. 2006. Last accessed December 4, 2006.</ref> The highest temperature ever recorded in St. Louis was {{convert|115|F}}, on July 14, 1954, while the lowest temperature on record is {{convert|-23|F}}, on January 29, 1873.<ref>[http://www.crh.noaa.gov/lsx/climate/top10.php#TOP%2010%20hottest%20days Welcome to the Top 10]. [[NOAA]]'s [[National Weather Service]] Weather Forecast Office. Last accessed December 4, 2006.</ref>

Winter is the driest season, averaging about 6 inches of total precipitation. Springtime (March through May), is typically the wettest season, with under 10.5 inches. Dry spells of one or two weeks' duration are common during the growing seasons.

[[Thunderstorm]]s can be expected on 40 to 50 days per year. A few of them will be severe with locally destructive winds and large [[hail]], and occasionally accompanied by tornadoes.<ref>{{Cite web|url=http://www.crh.noaa.gov/lsx/climate/torcli/stlouis.php|title=St. Louis, MO |author=<!--Not stated--> |website=NOAA's National Weather Service Weather Forecast Office |language=en-us |access-date=May 24, 2024}}</ref> A period of unseasonably warm weather late in Autumn known as [[Indian summer]] is common—[[rose]]s will still be in bloom as late as November or early December in some years.

===Other geography===
The largest natural lake in the county is [[Creve Coeur Lake]]. It was originally an oxbow of the nearby Missouri River and is now the centerpiece of a popular county park.

Manchester Road ([[Missouri Route 100|Route 100]]) follows an ancient path westward out of St. Louis, following the boundary between the [[Missouri River|Missouri]] and [[Meramec River|Meramec]] watersheds. It is one of only two routes to leave the county without crossing any rivers (the other being State Highway T).

The Sinks is a [[karst]] area in the far northern part of the county, with numerous [[sinkhole]]s.

==Demographics==
{{US Census population
|1820= 10049
|1830= 14125
|1840= 35979
|1850= 104978
|1860= 190524
|1870= 351189
|1880= 31888
|1890= 36307
|1900= 50040
|1910= 82417
|1920= 100737
|1930= 211593
|1940= 274230
|1950= 406349
|1960= 703532
|1970= 951353
|1980= 973896
|1990= 993529
|2000= 1016315
|2010= 998954
|2020= 1004125
|estyear=2023
|estimate=987059
|estref=<ref name="USCensusEst2023">{{cite web|title=Annual Estimates of the Resident Population for Counties: April 1, 2020 to July 1, 2023|url=https://www.census.gov/data/tables/time-series/demo/popest/2020s-counties-total.html|access-date=February 17, 2025}}</ref>
|align-fn=center
|footnote=Independent City of [[St. Louis]] seceded<br />from the County in 1876. Population<br />of the City of St. Louis in 1880<br />was 350,518.<br />
U.S. Decennial Census<ref>{{cite web|url=https://www.census.gov/programs-surveys/decennial-census.html|title=U.S. Decennial Census|publisher=United States Census Bureau|access-date=November 20, 2014}}</ref><br />1790–1960<ref>{{cite web|url=http://mapserver.lib.virginia.edu|title=Historical Census Browser|publisher=University of Virginia Library|access-date=November 20, 2014}}</ref> 1900–1990<ref>{{cite web|url=https://www.census.gov/population/cencounts/mo190090.txt|title=Population of Counties by Decennial Census: 1900 to 1990|publisher=United States Census Bureau|access-date=November 20, 2014}}</ref><br />1990–2000<ref>{{cite web|url=https://www.census.gov/population/www/cen2000/briefs/phc-t4/tables/tab02.pdf |archive-url=https://web.archive.org/web/20100327165705/http://www.census.gov/population/www/cen2000/briefs/phc-t4/tables/tab02.pdf |archive-date=March 27, 2010 |url-status=live|title=Census 2000 PHC-T-4. Ranking Tables for Counties: 1990 and 2000|publisher=United States Census Bureau|access-date=November 20, 2014}}</ref> 2010–2020<ref name="QF"/>
}}

As of the third quarter of 2024, the median home value in St. Louis County was $288,970.<ref>{{Cite web|title=County Median Home Price|url=https://www.nar.realtor/research-and-statistics/housing-statistics/county-median-home-prices-and-monthly-mortgage-payment|publisher=[[National Association of Realtors]]|access-date=February 17, 2025}}</ref>

As of the 2023 [[American Community Survey]], there are 414,739 estimated households in St. Louis County with an average of 2.36 persons per household. The county has a median household income of $81,340. Approximately 9.7% of the county's population lives at or below the [[Poverty in the United States|poverty line]]. St. Louis County has an estimated 65.1% employment rate, with 46.9% of the population holding a bachelor's degree or higher and 66.9% holding a high school diploma.<ref name="QF">{{Cite web|title=U.S. Census Bureau QuickFacts: St. Louis County, Missouri|url=https://www.census.gov/quickfacts/fact/table/stlouiscountymissouri/PST045224|access-date=February 17, 2025|website=www.census.gov|language=en}}</ref>

The top five reported ancestries (people were allowed to report up to two ancestries, thus the figures will generally add to more than 100%) were English (88.5%), Spanish (3.0%), Indo-European (4.1%), Asian and Pacific Islander (3.0%), and Other (1.4%).

The median age in the county was 40.6 years.

'''St. Louis County, Missouri – racial and ethnic composition'''<br><small>{{nobold|''Note: the US Census treats Hispanic/Latino as an ethnic category. This table excludes Latinos from the racial categories and assigns them to a separate category. Hispanics/Latinos may be of any race.''}}</small>
{| class="wikitable sortable collapsible" style="font-size: 95%;"
|-
! Race / ethnicity <small>(''NH = non-Hispanic'')</small>
! Pop. 1980<ref name=1980CensusScope>{{Cite web|title=St. Louis County, Missouri — Population by Race|url=https://censusscope.org/us/s29/c189/chart_race.html|publisher=CensusScope|access-date=February 17, 2025}}</ref> !! Pop. 1990<ref name=1990CensusScope>{{Cite web|title=St. Louis County, Missouri — Population by Race|url=https://censusscope.org/us/s29/c189/chart_race.html|publisher=CensusScope|access-date=February 17, 2025}}</ref> !! Pop. 2000<ref name=2000CensusP004>{{Cite web|title=P004: Hispanic or Latino, and Not Hispanic or Latino by Race – 2000: DEC Summary File 1 – St. Louis County, Missouri|url=https://data.census.gov/table/DECENNIALSF12000.P004?g=050XX00US29189|publisher=[[United States Census Bureau]]|access-date=February 17, 2025}}</ref> !! Pop. 2010<ref name=2010CensusP2>{{Cite web|title=P2: Hispanic or Latino, and Not Hispanic or Latino by Race – 2010: DEC Redistricting Data (PL 94-171) – St. Louis County, Missouri|url=https://data.census.gov/table?q=p2&g=050XX00US29189&tid=DECENNIALPL2010.P2|publisher=[[United States Census Bureau]]|access-date=February 17, 2025}}</ref> !! {{partial|Pop. 2020}}<ref name=2020CensusP2>{{Cite web|title=P2: Hispanic or Latino, and Not Hispanic or Latino by Race – 2020: DEC Redistricting Data (PL 94-171) – St. Louis County, Missouri|url=https://data.census.gov/cedsci/table?q=p2&g=050XX00US29189&tid=DECENNIALPL2020.P2|publisher=[[United States Census Bureau]]|access-date=February 17, 2025}}</ref>
|-
| [[Non-Hispanic or Latino whites|White]] alone (NH)
| 846,000<br>(86.87%) || 829,052<br>(83.45%) || 772,041<br>(75.96%) || 687,984<br>(68.87%) || style='background: #ffffe6; |624,703<br>(62.21%)
|-
| [[Non-Hispanic or Latino African Americans|Black or African American]] alone (NH)
| 108,984<br>(11.19%) || 138,786<br>(13.97%) || 192,544<br>(18.95%) || 231,801<br>(23.20%) || style='background: #ffffe6; |245,168<br>(24.42%)
|-
| [[Native Americans in the United States|Native American]] or [[Alaska Native]] alone (NH)
| 1,104<br>(0.11%) || 1,358<br>(0.14%) || 1,557<br>(0.15%) || 1,632<br>(0.16%) || style='background: #ffffe6; |1,474<br>(0.15%)
|-
| [[Asian Americans|Asian]] alone (NH)
| 7,916<br>(0.81%) || 13,936<br>(1.40%) || 22,492<br>(2.21%) || 34,466<br>(3.45%) || style='background: #ffffe6; |48,552<br>(4.84%)
|-
| [[Pacific Islander Americans|Pacific Islander]] alone (NH)
| — || — || 223<br>(0.02%) || 273<br>(0.03%) || style='background: #ffffe6; |264<br>(0.03%)
|-
| [[Race and ethnicity in the United States census|Other race]] alone (NH)
| 1,615<br>(0.17%) || 586<br>(0.06%) || 1,315<br>(0.13%) || 1,187<br>(0.12%) || style='background: #ffffe6; |4,736<br>(0.47%)
|-
| [[Multiracial Americans|Mixed race or multiracial]] (NH)
| — || — || 11,566<br>(1.14%) || 16,587<br>(1.66%) || style='background: #ffffe6; |42,050<br>(4.19%)
|-
| [[Hispanic and Latino Americans|Hispanic or Latino]] (any race)
| 8,277<br>(0.85%) || 9,811<br>(0.99%) || 14,577<br>(1.43%) || 25,024<br>(2.51%) || style='background: #ffffe6; |37,178<br>(3.70%)
|-
| '''Total'''
| '''973,896<br>(100.00%)''' || '''993,529<br>(100.00%)''' || '''1,016,315<br>(100.00%)''' || '''998,954<br>(100.00%)''' || style='background: #ffffe6; |'''1,004,125<br>(100.00%)'''
|}

===2020 census===
As of the [[2020 United States census|2020 census]], there were 1,004,125 people, 411,076 households, and 261,646 families in the county.<ref>{{Cite web|title=US Census Bureau, Table P16: Household Type |url=https://data.census.gov/table?q=St.%20Louis%20County,%20Missouri%20p16&y=2020 |access-date=February 17, 2025 |publisher=United States Census Bureau}}</ref> The [[population density]] was {{convert|1977.1|PD/sqmi|PD/km2|1}}. There were 444,653 housing units at an average density of {{convert|875.5|/sqmi|/km2|1}}. The racial makeup of the county was 62.97% [[White (U.S. Census)|White]], 24.56% [[African American (U.S. Census)|African American]], 0.24% [[Native American (U.S. Census)|Native American]], 4.86% [[Asian (U.S. Census)|Asian]], 0.03% [[Race (U.S. Census)|Pacific Islander]], 1.61% from some other races and 5.73% from two or more races. [[Hispanic and Latino Americans|Hispanic or Latino]] people of any race were 3.70% of the population.<ref>{{Cite web|title=How many people live in St. Louis County, Missouri |url=https://data.usatoday.com/census/total-population/total-population-change/st.-louis-county-missouri/050-29189/ |access-date=February 17, 2025 |publisher=USA Today}}</ref>

There were 411,076 households, out of which 53.46% had children under the age of 18 living with them, 44.55% were married couples living together, 14.55% had a female householder with no husband present, and 36.35% were non-families. 30.78% of all households were made up of individuals, and 5.57% had someone living alone who was 65 years of age or older. The average household size was 2.36 and the average family size was 3.05.

In the county, the age distribution of the population shows 21.88% under the age of 18, _% from 18 to 24, _% from 25 to 44, _% from 45 to 64, and _% who were 65 years of age or older. The median age was 40 years. For every 100 females, there were 90.00 males. For every 100 females age 18 and over, there were 85.70 males.

The median income for a household in the county was $58,532, and the median income for a family was $72,680. Males had a median income of $45,714 versus $30,278 for females. The [[per capita income]] for the county was $27,595. About 5.00% of families and 6.90% of the population were below the [[Poverty threshold|poverty line]], including 9.30% of those under age 18 and 5.30% of those age 65 or over.

==Economy==
===Top employers===
According to the county's 2023 Annual Comprehensive Financial Report,<ref>{{cite web|title=County of St. Louis – 2023 Annual Comprehensive Financial Report |url=https://stlouiscountymo.gov/st-louis-county-departments/administration/fiscal-transparency/annual-comprehensive-financial-reports-acfr/2023-financial-report/ |format=[[Portable Document Format|PDF]] |page=181 |date=February 17, 2025}}</ref> the largest employers in the county are:

{| class="wikitable"
|-
! #
! Employer
! # of Employees
! Percentage
|-
| 1
| [[Washington University in St. Louis]]
| 19,617
| 3.7%
|-
| 2
| [[Boeing Defense, Space & Security]]
| 15,796
| 3.0%
|-
| 3
| [[Mercy (healthcare organization)|Mercy Healthcare]]
| 15,084
| 2.9%
|-
| 4
| [[SSM Health|SSM Healthcare]]
| 14,226
| 2.7%
|-
| 5
| [[Schnucks|Schnucks Markets, Inc.]]
| 8,768
| 1.7%
|-
| 6
| [[Charter Communications]]
| 6,230
| 1.2%
|-
| 7
| [[Special School District of St. Louis County]]
| 5,890
| 1.1%
|-
| 8
| [[Edward Jones Investments|Edward Jones]]
| 5,514
| 1.0%
|-
| 9
| St. Louis County Government
| 4,994
| 0.9%
|-
| 10
| [[Centene Corporation]]
| 4,677
| 0.9%
|-
| —
| '''Total'''
| '''100,796'''
| '''19.1%'''
|}

===Unemployment rate===
The [[United States Department of Labor]]'s [[Bureau of Labor Statistics]] unemployment rate (not seasonally adjusted).<ref name="labor1">{{cite web |title=Local Area Unemployment Statistics – Missouri |publisher=Bureau of Labor Statistics |url=https://www.bls.gov/eag/eag.mo_stlouis_msa.htm |access-date=February 17, 2025}}</ref><ref name="labor2">{{cite web |title=Missouri Local Area Unemployment Statistics (LAUS) |publisher=Missouri Economic Research and Information Center (MERIC) |url=https://meric.mo.gov/data/economic/local-area-unemployment-statistics/laus |access-date=February 17, 2025}}</ref>

{| class=wikitable
|+ Unemployment in St. Louis County
! Calendar 2024
! Labor Force !! Employment !! Unemployment !! Unemployment Rate
|-
! December
| 542,369 || 525,422 || 16,947 || 3.1%
|-
! November
| 545,225 || 527,758 || 17,467 || 3.2%
|-
! October
| 547,919 || 529,681 || 18,238 || 3.3%
|-
! September
| 544,309 || 527,810 || 16,499 || 3.0%
|-
! August
| 550,976 || 529,958 || 21,018 || 3.8%
|-
! July
| 557,776 || 533,387 || 24,389 || 4.4%
|-
! June
| 548,648 || 526,436 || 22,212 || 4.0%
|-
! May
| 546,209 || 525,458 || 20,751 || 3.8%
|-
! April
| 543,967 || 526,791 || 17,176 || 3.2%
|-
! March
| 537,868 || 518,706 || 19,162 || 3.6%
|-
! February
| 533,156 || 513,339 || 19,817 || 3.7%
|-
! January
| 530,612 || 512,118 || 18,494 || 3.5%
|}

==Arts and culture==
{{see also|Cuisine of St. Louis}}

==Parks and recreation==
St. Louis County owns and maintains more than 40 parks as part of its county park system, including playgrounds and nature preserves. It also operates several recreation centers, the [[National Museum of Transportation]], and the Affton Community Center. In addition to parks owned by St. Louis County, the county is home to three [[List of Missouri state parks|Missouri state parks]]: [[Babler State Park|Babler]], [[Castlewood State Park|Castlewood]], and [[Route 66 State Park]], and part of the [[Big Muddy National Fish and Wildlife Refuge]] and the [[Ulysses S. Grant National Historic Site]]. Several municipalities in the county also own and maintain their own park systems.

{| class="wikitable collapsible collapsed sortable" style="width: 100%;"
|+ Parks owned by St. Louis County
|-
! Name!!Area (acres)!!class="unsortable"|Region of St. Louis County†
|-
| [[Bee Tree Park]]|| 199 || South
|-
| [[Bella Fontaine Park]]|| 300 || North
|-
| [[Daniel Bissell House|Bissell House]]|| 9.3 || North
|-
| [[Black Forest Park]]|| 4.3 || South
|-
| [[Bohrer Park]] || 16 || South
|-
| [[Bon Oak Park]]|| 15 || North
|-
| [[Buder Park]]|| 75 || South
|-
| [[Castlepoint Park]]|| 11 || North
|-
| [[Cliff Cave Park]] || 560 || South
|-
| [[Clydesdale Park]]|| 117 || South
|-
| [[Creve Coeur Park]] || 2,114 || West
|-
| [[Kraus House|Ebsworth Park]] || 10.5 || West
|-
| [[Endicott Park]]|| 24 || North
|-
| [[Faust Park]] || 197 || West
|-
| [[Endicott Park]]|| 24 || North
|-
| [[Fort Bellefontaine|Fort Bellefontaine Park]] || 305.6 || North
|-
| [[Greensfelder County Park]] || 1,646 || West
|-
| [[Jefferson Barracks Park]]|| 426 || South
|-
| [[King Park (St. Louis County, Missouri)|King Park]]|| 4 || North
|-
| [[Kinloch Park]]|| 9 || North
|-
| [[Laumeier Sculpture Park]] || 105 || South
|-
| [[Larimore Park]]|| 22 || North
|-
| [[Lemay Park]]|| 18.5 || South
|-
| [[Lone Elk County Park]] || 546 || West
|-
| [[Love Park (St. Louis County, Missouri)|Love Park]]|| 89 || West
|-
| [[Mathilda-Welmering Park]]|| 6 || South
|-
| [[McDonnell Park]] || 133 || North
|-
| [[Memorial Park (St. Louis County, Missouri)|Memorial Park]]|| 2.7 || North
|-
| [[Ohlendorf Park]]|| 10 || South
|-
| [[Queeny Park]] || 564 || West
|-
| [[Sioux Passage Park]]|| 188 || North
|-
| [[Simpson Park (St. Louis County, Missouri)|Simpson Park]]|| 206 || South
|-
| [[Spanish Lake Park]]|| 245 || North
|-
| [[Stacy Park]] || 35 || West
|-
| [[St. Vincent Park]]|| 133 || North
|-
| [[Suson Park]]|| 98 || South
|-
| [[Sylvan Springs Park]]|| 70 || South
|-
| [[Tilles Park (St. Louis County, Missouri)|Tilles Park]] || 75 || West
|-
| [[Unger Park]]|| 140 || South
|-
| [[Veterans Memorial Park (St. Louis County, Missouri)|Veterans Memorial Park]]|| 250 || North
|-
| [[West Tyson County Park]] || 670 || West
|-
| [[Winter Park (St. Louis County, Missouri)|Winter Park]]|| 160 || South
|-class="sortbottom"
| colspan="3" style="font-size: 8pt"| † Regions of St. Louis County as defined by the St. Louis County Parks and Recreation Department.
|}

==Government==
St. Louis County government is divided between [[Executive (government)|executive]] power vested in the [[List of county executives of St. Louis County, Missouri|County Executive]] and [[Legislature|legislative]] power vested in the [[St. Louis County Council|County Council]]. The current county executive is Sam Page, who was appointed on April 29, 2019. The county executive's term is four years without term limits, and the position is elected by the population of the entire county. The council consists of seven members elected from separate districts within the county, with four-year terms beginning on January 1 following elections. In 1950, St. Louis County became the first Missouri county to adopt a home-rule [[charter]] under the [[Constitution of Missouri|Missouri Constitution]], and the current charter was adopted by voters on November 6, 1979.<ref>{{Cite web |title=Municode Library |url=https://library.municode.com/mo/st._louis/codes/code_of_ordinances?nodeId=CH |access-date=October 7, 2024 |website=library.municode.com}}</ref>

{{Missouri county elected officials
| name = St. Louis County, Missouri
| assessor = [[Jake Zimmerman]]
| assessorparty = Democratic
| countyexecutive = [[Sam Page (politician)|Sam Page]]
| countyexecutiveparty = Democratic
| prosecutor = Melissa Price Smith
| prosecutorparty = Democratic
}}

===Public safety===
The [[St. Louis County Police Department]] operates under the authority of the [[St. Louis County Board of Police Commissioners]] and is the largest law enforcement agency in St. Louis County.{{citation needed|date=November 2012}} Although it is directly responsible for law enforcement in unincorporated areas of the county, several municipalities contract with the county police for public safety services.<ref name="stlcopolicecontracts">{{Cite web|url=http://www.stlouisco.com/Portals/8/docs/Document%20Library/police/Contracts.pdf |title=St. Louis county police department police service agreements & assignments |archive-url=https://web.archive.org/web/20140921072928/http://www.stlouisco.com/Portals/8/docs/Document%20Library/police/Contracts.pdf |archive-date=September 21, 2014}}</ref> Municipalities that maintain service agreements with the county police are Black Jack, Fenton, [[Ferguson Police Department (Missouri)|Ferguson]], Grantwood Village, Green Park, Hanley Hills, Jennings, Marlborough, Norwood Court, Pasadena Hills, Twin Oaks, Valley Park, Wilbur Park, and Wildwood.<ref name="stlcopolicecontracts"/> A total of 58 of the 90 municipalities in the county maintain their own police departments. Eighty-one of the local towns run their own courts.<ref>{{cite news|title=Editorial: Erase arbitrary boundaries to build a greater St. Louis|work=Post-Dispatch|date=March 28, 2015}}</ref>

St. Louis County fire services are provided by 20 municipal fire departments and 23 fire protection districts.<ref name="firedistricts">{{Cite web|url=http://www.stlouisco.com/YourGovernment/OtherGovernmentAgencies/CountyFireDistricts|title=Municipal Fire Departments {{!}} Fire Protection Districts {{!}} Countywide Map|last=Government|first=St. Louis County|website=www.stlouisco.com|language=en-US|access-date=March 26, 2018|archive-date=November 14, 2012|archive-url=https://web.archive.org/web/20121114221358/http://www.stlouisco.com/YourGovernment/OtherGovernmentAgencies/CountyFireDistricts|url-status=dead}}</ref> The fire protection districts exist as independent, taxing governments that are unrelated to the St. Louis County government, while the municipal fire departments are funded through municipal taxes and are administered by their respective cities.<ref name="firedistricts"/>
{{wide image|St Louis County MO Government Center rectilinear1.jpg|800px|County government buildings in Clayton. From left to right: County Police headquarters, the Lawrence K. Roos County Government Building, the Buzz Westfall Justice Center, and the Courts Building}}

{| class="wikitable" style="font-size:95%;"
|+ Past gubernatorial election results<ref>{{cite web|url=https://stlouiscountymo.gov/st-louis-county-government/board-of-elections/election-results-archive/#2020 |title=Election Results Archive |access-date=March 1, 2022 |archive-date=July 28, 2021 |archive-url=https://web.archive.org/web/20210728200224/https://stlouiscountymo.gov/st-louis-county-government/board-of-elections/election-results-archive/#2020 |url-status=dead}}</ref>
|- bgcolor=lightgrey
! Year
! [[Republican Party (United States)|Republican]]
! [[Democratic Party (United States)|Democratic]]
! [[Third Party (United States)|Third Parties]]
|-
|align="center" bgcolor="#fff3f3"|[[2024 Missouri gubernatorial election|2024]]
|align="center" bgcolor="#fff3f3"|40.25% ''201,181''
|align="center" bgcolor="#f0f0ff"|'''57.81%''' ''288,946''
|align="center" |1.94% ''9,694''
|-
| align="center" bgcolor="#fff3f3"|[[2020 Missouri gubernatorial election|2020]]
| align="center" bgcolor="#fff3f3"|38.77% ''207,535
| align="center" bgcolor="#f0f0ff"|'''59.28%''' ''317,327''
| align="center" |1.95% ''10,413''
|-
| align="center" bgcolor="#fff3f3"|[[2016 Missouri gubernatorial election|2016]]
| align="center" bgcolor="#fff3f3"|38.76% ''199,827''
| align="center" bgcolor="#f0f0ff"|'''58.40%''' ''301,115''
| align="center" |2.77% ''14,299''
|-
| align="center" bgcolor="#f0f0ff"|[[2012 Missouri gubernatorial election|2012]]
| align="center" bgcolor="#fff3f3"|35.62% ''185,704''
| align="center" bgcolor="#f0f0ff"|'''62.30%''' ''324,748''
| align="center" |3.85% ''19,652''
|-
| align="center" bgcolor="#f0f0ff"|[[2008 Missouri gubernatorial election|2008]]
| align="center" bgcolor="#fff3f3"|32.92% ''180,278''
| align="center" bgcolor="#f0f0ff"|'''65.32%''' ''357,649''
| align="center" |1.71% ''9,396''
|-
| align="center" bgcolor="#fff3f3"|[[2004 Missouri gubernatorial election|2004]]
| align="center" bgcolor="#fff3f3"|44.09% ''238,783''
| align="center" bgcolor="#f0f0ff"|'''54.77%''' ''296,624''
| align="center" |1.13% ''6,127''
|-
| align="center" bgcolor="#f0f0ff"|[[2000 Missouri gubernatorial election|2000]]
| align="center" bgcolor="#fff3f3"|48.01% ''233,031''
| align="center" bgcolor="#f0f0ff"|'''49.31%''' ''239,341''
| align="center" |2.68% ''12,997''
|-
| align="center" bgcolor="#f0f0ff"|[[1996 Missouri gubernatorial election|1996]]
| align="center" bgcolor="#fff3f3"|45.09% ''208,184''
| align="center" bgcolor="#f0f0ff"|'''53.12%''' ''245,275''
| align="center" |1.79% ''8,259''
|}

===Politics===
{{PresHead|place=St. Louis County, Missouri|source=<ref>{{Cite web|url=http://uselectionatlas.org/RESULTS|title=Dave Leip's Atlas of U.S. Presidential Elections|last=Leip|first=David|website=uselectionatlas.org|access-date=March 26, 2018}}</ref>}}
<!-- PresRow should be {{PresRow|Year|Winning party|GOP vote #|Dem vote #|3rd party vote #|State}} -->
{{PresRow|1888|Republican|4,416|2,707|53|Missouri}}
{{PresRow|1892|Republican|4,367|3,116|69|Missouri}}
{{PresRow|1896|Republican|6,210|3,403|76|Missouri}}
{{PresRow|1900|Republican|6,537|3,864|172|Missouri}}
{{PresRow|1904|Republican|7,375|2,870|374|Missouri}}
{{PresRow|1908|Republican|10,177|4,522|627|Missouri}}
{{PresRow|1912|Republican|6,177|5,409|3,940|Missouri}}
{{PresRow|1916|Republican|12,485|7,587|594|Missouri}}
{{PresRow|1920|Republican|25,008|12,438|1,896|Missouri}}
{{PresRow|1924|Republican|26,669|16,075|5,090|Missouri}}
{{PresRow|1928|Republican|42,572|33,802|293|Missouri}}
{{PresRow|1932|Democratic|35,872|59,044|3,341|Missouri}}
{{PresRow|1936|Democratic|45,541|63,226|3,333|Missouri}}
{{PresRow|1940|Republican|66,909|52,380|458|Missouri}}
{{PresRow|1944|Republican|64,131|57,780|355|Missouri}}
{{PresRow|1948|Republican|69,592|62,684|1,107|Missouri}}
{{PresRow|1952|Republican|116,821|95,457|202|Missouri}}
{{PresRow|1956|Republican|138,111|121,881|0|Missouri}}
{{PresRow|1960|Democratic|157,992|166,508|0|Missouri}}
{{PresRow|1964|Democratic|134,962|213,658|0|Missouri}}
{{PresRow|1968|Republican|180,355|165,786|39,234|Missouri}}
{{PresRow|1972|Republican|264,147|160,801|0|Missouri}}
{{PresRow|1976|Republican|246,988|196,915|8,723|Missouri}}
{{PresRow|1980|Republican|263,518|192,796|28,517|Missouri}}
{{PresRow|1984|Republican|307,684|173,144|0|Missouri}}
{{PresRow|1988|Republican|262,784|216,534|1,364|Missouri}}
{{PresRow|1992|Democratic|188,285|235,760|110,718|Missouri}}
{{PresRow|1996|Democratic|196,096|225,524|40,658|Missouri}}
{{PresRow|2000|Democratic|224,689|250,631|11,564|Missouri}}
{{PresRow|2004|Democratic|244,969|295,284|2,730|Missouri}}
{{PresRow|2008|Democratic|221,705|333,123|5,026|Missouri}}
{{PresRow|2012|Democratic|224,742|297,097|8,277|Missouri}}
{{PresRow|2016|Democratic|202,434|286,704|30,548|Missouri}}
{{PresRow|2020|Democratic|199,493|328,151|8,802|Missouri}}
{{PresRow|2024|Democratic|187,982|305,635|9,121|Missouri}}
{{PresFoot}}

As of March 2016, there were 648,073 registered voters in St. Louis County, down from 708,283 registered voters in April 2013.<ref>{{cite web|url=http://www.stlouisco.com/Portals/8/docs/document%20library/elections/eresults/el160315/el45.htm|title=Presidential Preference Primary, Official Results|publisher=St. Louis County|date=March 25, 2016|access-date=March 31, 2016|archive-date=April 9, 2016|archive-url=https://web.archive.org/web/20160409225017/http://www.stlouisco.com/Portals/8/docs/document%20library/elections/eresults/el160315/el45.htm|url-status=dead}}</ref><ref>{{cite web |url=http://www.stlouisco.com/portals/8/docs/document%20library/elections/eresults/el130402/el45.html |title=General Municipal Election |publisher=St. Louis County |date=April 2, 2013 |access-date=June 20, 2013 |archive-date=April 29, 2013 |archive-url=https://web.archive.org/web/20130429130539/http://www.stlouisco.com/portals/8/docs/document%20library/elections/eresults/el130402/el45.html |url-status=dead }}</ref><ref>{{Cite news |title=St. Louis County Police Department Police Service Agreements and Assignments |work=St. Louis County}}</ref> At the federal level, the county is represented by [[Democratic Party (United States)|Democrat]] [[Wesley Bell]] of the [[Missouri's 1st congressional district|1st district]], and [[Republican Party (United States)|Republican]] [[Ann Wagner]] of the [[Missouri's 2nd congressional district|2nd district]].

Since 1992, the county has favored Democratic candidates in the presidential elections. Democrats are generally strongest in the northern portion of the county, which has a high [[African Americans|Black]] population, while Republicans have historically dominated the western and southern parts of the county. In recent years however, Republicans have seen the western and southern portion of the county, made up of suburbs, become much more competitive. St. Louis County is a diverse, college-educated, suburban, and affluent county, with a large Black population, as well as a new influx of Asian Americans. These factors in recent years have pushed the county to become safer for Democrats. Historically, the [[Republican Party (United States)|Republican]] voters in this area were more moderate voters, fiscally conservative yet socially liberal. St Louis County overall is a Democratic stronghold, having voted for the Democratic presidential nominee in each election since [[1992 United States presidential election|1992]], and with increasing margins since [[2000 United States presidential election|2000]]. In 2004, 2012, 2016, and 2020, it was only one of four counties in the state to vote Democratic. In [[2020 United States presidential election|2020]], [[Joe Biden]] won the county with over 60% of the vote, the best ever showing for a Democrat in the county.

As of the 2022 elections, of the five senators (who have residences in St. Louis County) elected to the [[Missouri Senate]], four are Democrats and one is a Republican. Of the 27 representatives elected to the [[Missouri House of Representatives]], 19 are Democrats and 8 are Republicans.<ref>{{cite web|date=November 18, 2014|publisher=St. Louis County Board of Elections|title=General Election, Official Final Results|url=http://www.stlouisco.com/portals/8/docs/document%20library/elections/eresults/el141104/el45.htm|access-date=March 31, 2016|archive-date=April 4, 2016|archive-url=https://web.archive.org/web/20160404191154/http://www.stlouisco.com/portals/8/docs/document%20library/elections/eresults/el141104/el45.htm|url-status=dead}}</ref> All of North County elects Democrats to the [[Missouri General Assembly]], most of Mid County also elect Democrats, while most of West County and South County elects Republicans.

==Education==
Education in St. Louis County is provided by 23 public [[school districts]], 20 private high schools, both a unified [[public library]] system and several municipal libraries, and several colleges and universities. Several of the school districts in the county also maintain a voluntary student transfer agreement with the [[St. Louis Public Schools]] that allows county residents to attend [[magnet school]]s in the city of St. Louis.

===Public schools===
School districts include:<ref>{{cite map|author=Geography Division|url=https://www2.census.gov/geo/maps/DC2020/PL20/st29_mo/schooldistrict_maps/c29189_st_louis/DC20SD_C29189.pdf |archive-url=https://web.archive.org/web/20220722211227/https://www2.census.gov/geo/maps/DC2020/PL20/st29_mo/schooldistrict_maps/c29189_st_louis/DC20SD_C29189.pdf |archive-date=July 22, 2022 |url-status=live|title=2020 CENSUS - SCHOOL DISTRICT REFERENCE MAP: St. Louis County, MO|publisher=[[U.S. Census Bureau]]|date=January 12, 2021|accessdate=July 22, 2022}} - [https://www2.census.gov/geo/maps/DC2020/PL20/st29_mo/schooldistrict_maps/c29189_st_louis/DC20SD_C29189_SD2MS.txt Text list]</ref>
{{columns-list|colwidth=20em|
*[[Affton School District]]
*[[Bayless School District]]
*[[Brentwood School District]]
*[[School District of Clayton]]
*[[Ferguson-Florissant School District]]
*[[Hancock Place School District]]
*[[Hazelwood School District]]
*[[Jennings School District]]
*[[Kirkwood School District]]
*[[Ladue School District]]
*[[Lindbergh Schools]]
*[[Maplewood Richmond Heights School District]]
*[[Mehlville School District]]
*[[Meramec Valley R-III School District]]
*[[Normandy Schools Collaborative]]
*[[Parkway School District]]
*[[Pattonville School District]]
*[[Ritenour School District]]
*[[Riverview Gardens School District]]
*[[Rockwood School District]]
*[[School District of University City]]
*[[Valley Park School District]]
*[[Webster Groves School District]]
}}

[[Special School District of St. Louis County]] (SSD) operates schools for differently abled students.<ref>{{cite web|url=https://www.ssdmo.org/Page/62|title=SSD Mission & Vision|publisher=[[Special School District of St. Louis County]]|accessdate=July 22, 2022|quote=12110 Clayton Road, Town & Country, MO 63131}}</ref>

The Berkeley and Kinloch districts merged into Ferguson-Florissant in 1975. [[Wellston School District]] closed in 2010 and was consolidated into the Normandy district.<ref>{{cite news|url=https://www.stlpr.org/education/2009-12-17/missouri-school-board-votes-to-merge-wellston-school-district-into-normandy|title=Missouri school board votes to merge Wellston school district into Normandy |publisher=[[St. Louis Public Radio]]|date=2009-12-17|access-date=2025-06-01}}</ref>

===Private schools===
{{columns-list|colwidth=20em|
*[[Barat Academy]]
*[[Chaminade College Preparatory School (Missouri)|Chaminade College Preparatory School]] ''(All Boys)''
*[[Christian Brothers College High School]] ''(All Boys)''
*[[Cor Jesu Academy]] ''(All Girls)''
*[[De Smet Jesuit High School]] ''(All Boys)''
*[[Incarnate Word Academy (Bel-Nor, Missouri)|Incarnate Word Academy]] ''(All Girls)''
*[[John Burroughs School]]
*[[Lutheran High School North (Missouri)|Lutheran High School North]]
*[[Lutheran High School South]]
*[[Mary Institute and St. Louis Country Day School]]
*[[Nerinx Hall High School]] ''(All Girls)''
*[[The Principia]]
*[[Saint Louis Priory School]] ''(All Boys)''
*[[St. John Vianney High School (Kirkwood, Missouri)|St. John Vianney High School]] ''(All Boys)''
*[[St. Joseph's Academy (St. Louis)|St. Joseph's Academy]] ''(All Girls)''
*[[Ursuline Academy (Oakland, Missouri)|Ursuline Academy]] ''(All Girls)''
*[[Villa Duchesne and Oak Hill School|Villa Duchesne]] ''(All Girls)''
*[[Visitation Academy of St. Louis]] ''(All Girls)''
*[[Westminster Christian Academy (Missouri)|Westminster Christian Academy]]
*[[Whitfield School]]
}}

===Higher education===
{{columns-list|colwidth=20em|
*[[Concordia Seminary]]
*[[Eden Theological Seminary]]
*[[Fontbonne University]]
*[[Kenrick–Glennon Seminary]]
*[[Logan University]]
*[[Maryville University]]
*[[Missouri Baptist University]]
*[[St. Louis Christian College]]
*[[Saint Louis University]]
*[[St. Louis Community College]]
*[[University of Missouri–St. Louis]]
*[[Washington University in St. Louis]]
*[[Webster University]]
}}

===Library===
St. Louis County libraries include the unified [[St. Louis County Library]] and several municipal library systems.

==Infrastructure==

===Transportation===
====Major freeways and highways====
*{{jct|state=MO|I|44}}
**{{jct|state=MO|BL|44|dab1=Pacific|name1=Pacific}}
*{{jct|state=MO|I|55}}
*{{jct|state=MO|I|64|US|40}}
*{{jct|state=MO|I|70}}
*{{jct|state=MO|I|170}}
*{{jct|state=MO|I|255}}
*{{jct|state=MO|I|270}}
*{{jct|state=MO|US|50}}
*{{jct|state=MO|US|61}}
*{{jct|state=MO|US|67}}
*{{jct|state=MO|MO|21}}
*{{jct|state=MO|MO|30}}
*{{jct|state=MO|MO|100}}
*{{jct|state=MO|MO|115}}
*{{jct|state=MO|MO|141}}
*{{jct|state=MO|MO|180}}
*{{jct|state=MO|MO|231}}
*{{jct|state=MO|MO|267}}
*{{jct|state=MO|MO|340}}
*{{jct|state=MO|MO|364}}
*{{jct|state=MO|MO|366}}
*{{jct|state=MO|MO|367}}
*{{jct|state=MO|MO|370}}

===Health care===
In 1927, a $1 million bond was issued allocating funds for the construction of the first St. Louis County Hospital.<ref>"[http://www.co.st-louis.mo.us/DOH/history.html#foundation History of St. Louis County Hospital]." St. Louis County Health. Retrieved on August 24, 2009. {{webarchive |url=https://web.archive.org/web/20090131141004/http://www.co.st-louis.mo.us/DOH/history.html#foundation |date=January 31, 2009}}</ref> Construction of the 200-bed, the non-segregated hospital began in 1929 in the city of Clayton. The hospital opened in July 1931 and ran until June 1986.<ref>"[http://beckerexhibits.wustl.edu/mowihsp/win/Timeline/CountyHosp.htm History of St. Louis County Hospital]." Washington University School of Medicine, St. Louis. Retrieved on August 24, 2009.</ref>

Current list of hospitals in St. Louis County:
{|
|- valign="top"
|
*[[Barnes–Jewish West County Hospital]]
*[[Christian Hospital]]
*dePaul Health Center - Bridgeton
*Des Peres Hospital - Des Peres
*DuBuis Hospital of St. Louis
*[[Mercy Hospital South]] - Mehlville
*[[Mercy Hospital Creve Coeur]]
*[[Missouri Baptist Medical Center]] - Town & Country
*Northwest HealthCare
*[[Ranken Jordan Pediatric Bridge Hospital]] - Maryland Heights
|
*St. Clare Hospital - Fenton
*St. John's Mercy Medical Center - Creve Coeur
*[[St. Luke's Hospital (Chesterfield, Missouri)|St. Luke's Hospital]] - Chesterfield
*St. Mary's Hospital - Richmond Heights
|
|}

==Communities==
{{see also|Municipalities of St. Louis County, Missouri}}
One-third of the county population lives in [[unincorporated area]]s, for which the county government provides services such as zoning, code enforcement, refuse disposal, and police protection. In addition to the county-level government, there are 87 [[municipalities of St. Louis County, Missouri|municipal governments in St. Louis County]] that also provide services.<ref name="stlcomunislist">{{Cite web |last=Stefanescu |first=Victor |date=August 9, 2023 |title=Glen Echo Park to merge with Normandy following landslide vote |url=https://www.stltoday.com/news/local/government-politics/glen-echo-park-to-merge-with-normandy-following-landslide-vote/article_95b960ca-363c-11ee-bbec-8763296a9ffb.html |access-date=August 16, 2024 |website=STLtoday.com |language=en}}</ref> These vary widely in population and area. The smallest towns in population are [[Champ, Missouri|Champ]] with a 2020 population of 10,<ref name="Census 2020">{{cite web |url=https://www.census.gov/content/census/en/search-results.html?stateGeo=none&q=Champ%20village,%20Missouri&searchtype=web|title=2020 Decennial Census, Champ village, Missouri |publisher=[[United States Census Bureau]] |access-date=May 23, 2022 }}</ref> [[Country Life Acres, Missouri|Country Life Acres]] (population 74),<ref name=censusx>{{cite web| url=https://www.census.gov| title=Race, Hispanic or Latino, Age, and Housing Occupancy: 2010 Census Redistricting Data (Public Law 94-171) Summary File (QT-PL), Champ village, Missouri| publisher=[[United States Census Bureau]]| access-date=October 25, 2011}}</ref> and [[Mackenzie, Missouri|Mackenzie]] (population 134);<ref name=censusx/> 14 county municipalities have a 2010 population under 500, and fewer than a third exceed 10,000. In area, the smallest town is Mackenzie ({{convert|12.8|acre|ha||lk=on}}) while 14 other towns are {{convert|0.1|mi2|km2}} or less. At the other end of the scale, [[Florissant, Missouri|Florissant]] has a population over 50,000, and [[Wildwood, Missouri|Wildwood]] at the far west of the county is {{convert|66|sqmi}}.
 
St. Louis County municipalities include:

===Cities===
{{div col|colwidth=15em}}
*[[Ballwin, Missouri|Ballwin]]
*[[Bella Villa, Missouri|Bella Villa]]
*[[Bellefontaine Neighbors, Missouri|Bellefontaine Neighbors]]
*[[Bellerive Acres, Missouri|Bellerive Acres]]
*[[Bel-Nor, Missouri|Bel-Nor]]
*[[Bel-Ridge, Missouri|Bel-Ridge]]
*[[Berkeley, Missouri|Berkeley]]
*[[Beverly Hills, Missouri|Beverly Hills]]
*[[Black Jack, Missouri|Black Jack]]
*[[Breckenridge Hills, Missouri|Breckenridge Hills]]
*[[Brentwood, Missouri|Brentwood]]
*[[Bridgeton, Missouri|Bridgeton]]
*[[Calverton Park, Missouri|Calverton Park]]
*[[Charlack, Missouri|Charlack]]
*[[Chesterfield, Missouri|Chesterfield]]
*[[Clarkson Valley, Missouri|Clarkson Valley]]
*[[Clayton, Missouri|Clayton]] (county seat)
*[[Cool Valley, Missouri|Cool Valley]]
*[[Country Club Hills, Missouri|Country Club Hills]]
*[[Crestwood, Missouri|Crestwood]]
*[[Creve Coeur, Missouri|Creve Coeur]]
*[[Crystal Lake Park, Missouri|Crystal Lake Park]]
*[[Dellwood, Missouri|Dellwood]]
*[[Des Peres, Missouri|Des Peres]]
*[[Edmundson, Missouri|Edmundson]]
*[[Ellisville, Missouri|Ellisville]]
*[[Eureka, Missouri|Eureka]] (Partly in [[Jefferson County, Missouri|Jefferson County]])
*[[Fenton, Missouri|Fenton]]
*[[Ferguson, Missouri|Ferguson]]
*[[Flordell Hills, Missouri|Flordell Hills]]
*[[Florissant, Missouri|Florissant]]
*[[Frontenac, Missouri|Frontenac]]
*[[Glendale, Missouri|Glendale]]
*[[Green Park, Missouri|Green Park]]
*[[Greendale, Missouri|Greendale]]
*[[Hazelwood, Missouri|Hazelwood]]
*[[Huntleigh, Missouri|Huntleigh]]
*[[Jennings, Missouri|Jennings]]
*[[Kinloch, Missouri|Kinloch]]
*[[Kirkwood, Missouri|Kirkwood]]
*[[Ladue, Missouri|Ladue]]
*[[Lakeshire, Missouri|Lakeshire]]
*[[Manchester, Missouri|Manchester]]
*[[Maplewood, Missouri|Maplewood]]
*[[Maryland Heights, Missouri|Maryland Heights]]
*[[Moline Acres, Missouri|Moline Acres]]
*[[Normandy, Missouri|Normandy]]
*[[Northwoods, Missouri|Northwoods]]
*[[Oakland, Missouri|Oakland]]
*[[Olivette, Missouri|Olivette]]
*[[Overland, Missouri|Overland]]
*[[Pacific, Missouri|Pacific]] (mostly in [[Franklin County, Missouri|Franklin County]])
*[[Pagedale, Missouri|Pagedale]]
*[[Pasadena Hills, Missouri|Pasadena Hills]]
*[[Pine Lawn, Missouri|Pine Lawn]]
*[[Richmond Heights, Missouri|Richmond Heights]]
*[[Riverview, St. Louis County, Missouri|Riverview]]
*[[Rock Hill, Missouri|Rock Hill]]
*[[Shrewsbury, Missouri|Shrewsbury]]
*[[St. Ann, Missouri|St. Ann]]
*[[St. John, Missouri|St. John]]
*[[Sunset Hills, Missouri|Sunset Hills]]
*[[Town and Country, Missouri|Town and Country]]
*[[Twin Oaks, Missouri|Twin Oaks]]
*[[University City, Missouri|University City]]
*[[Valley Park, Missouri|Valley Park]]
*[[Velda City, Missouri|Velda City]]
*[[Velda Village Hills, Missouri|Velda Village Hills]]
*[[Vinita Park, Missouri|Vinita Park]]
*[[Warson Woods, Missouri|Warson Woods]]
*[[Webster Groves, Missouri|Webster Groves]]
*[[Wellston, Missouri|Wellston]]
*[[Wildwood, Missouri|Wildwood]]
*[[Winchester, Missouri|Winchester]]
*[[Woodson Terrace, Missouri|Woodson Terrace]]
{{div col end}}

===Villages===
{{div col|colwidth=15em}}
*[[Champ, Missouri|Champ]]
*[[Country Life Acres, Missouri|Country Life Acres]]
*[[Grantwood Village, Missouri|Grantwood Village]]
*[[Hanley Hills, Missouri|Hanley Hills]]
*[[Hillsdale, Missouri|Hillsdale]]
*[[Marlborough, Missouri|Marlborough]]
*[[Norwood Court, Missouri|Norwood Court]]
*[[Pasadena Park, Missouri|Pasadena Park]]
*[[Sycamore Hills, Missouri|Sycamore Hills]]
*[[Uplands Park, Missouri|Uplands Park]]
*[[Westwood, Missouri|Westwood]]
*[[Wilbur Park, Missouri|Wilbur Park]]
{{div col end}}

===Census-designated places===
{{div col|colwidth=22em}}
*[[Affton, Missouri|Affton]]
*[[Castle Point, Missouri|Castle Point]]
*[[Concord, Missouri|Concord]]
*[[Glasgow Village, Missouri|Glasgow Village]]
*[[Lemay, Missouri|Lemay]]
*[[Mehlville, Missouri|Mehlville]]
*[[Oakville, Missouri|Oakville]]
*[[Old Jamestown, Missouri|Old Jamestown]]
*[[St. George, Missouri | St. George]]
*[[Sappington, Missouri|Sappington]]
*[[Spanish Lake, Missouri|Spanish Lake]]
{{div col end}}

===Townships===
{{div col|colwidth=22em}}
* [[Airport Township, St. Louis County, Missouri|Airport]]
* [[Bonhomme Township, St. Louis County, Missouri|Bonhomme]]
* [[Chesterfield Township, St. Louis County, Missouri|Chesterfield]]
* [[Clayton Township, St. Louis County, Missouri|Clayton]]
* [[Concord Township, St. Louis County, Missouri|Concord]]
* [[Creve Coeur Township, St. Louis County, Missouri|Creve Coeur]]
* [[Ferguson Township, St. Louis County, Missouri|Ferguson]]
* [[Florissant Township, St. Louis County, Missouri|Florissant]]
* [[Gravois Township, St. Louis County, Missouri|Gravois]]
* [[Hadley Township, St. Louis County, Missouri|Hadley]]
* [[Jefferson Township, St. Louis County, Missouri|Jefferson]]
* [[Lafayette Township, St. Louis County, Missouri|Lafayette]]
* [[Lemay Township, St. Louis County, Missouri|Lemay]]
* [[Lewis and Clark Township, St. Louis County, Missouri|Lewis and Clark]]
* [[Maryland Heights Township, St. Louis County, Missouri|Maryland Heights]]
* [[Meramec Township, St. Louis County, Missouri|Meramec]]
* [[Midland Township, St. Louis County, Missouri|Midland]]
* [[Missouri River Township, St. Louis County, Missouri|Missouri River]]
* [[Normandy Township, St. Louis County, Missouri|Normandy]]
* [[Northwest Township, St. Louis County, Missouri|Northwest]]
* [[Norwood Township, St. Louis County, Missouri|Norwood]]
* [[Oakville Township, St. Louis County, Missouri|Oakville]]
* [[Queeny Township, St. Louis County, Missouri|Queeny]]
* [[Spanish Lake Township, St. Louis County, Missouri|Spanish Lake]]
* [[St. Ferdinand Township, St. Louis County, Missouri|St. Ferdinand]]
*[[Tesson Ferry Township, St. Louis County, Missouri|Tesson Ferry]]
*[[University Township, St. Louis County, Missouri|University]]
* [[Wildhorse Township, St. Louis County, Missouri|Wildhorse]]
{{div col end}}

===Unincorporated communities===
{{div col|colwidth=22em}}
* [[Ascalon, Missouri|Ascalon]]
* [[Carsonville, Missouri|Carsonville]]
* [[Earth City, Missouri|Earth City]]
* [[Fort Belle Fontaine]]
* [[Glencoe, Missouri|Glencoe]]
* [[Grover, Missouri|Grover]]
* [[MacKenzie, Missouri|Mackenzie]]
* [[Peerless Park, Missouri|Peerless Park]]
* [[Pond, Missouri|Pond]]
* [[Sherman, Missouri|Sherman]]
* [[Times Beach, Missouri|Times Beach]]
{{div col end}}

==See also==
* [[List of counties in Missouri]]
* [[National Register of Historic Places listings in St. Louis County, Missouri]]

==References==
{{Reflist|30em}}

==External links==
{{commons category}}
* [https://stlouiscountymo.gov/ St. Louis County – Government]
* [https://www.danbrassil.com/neighborhoods/st-louis-county/ St. Louis County – Neighborhoods]
* [https://www.weather.gov/lsx/cli_of_stl The Climatology of the St. Louis Area]
* [https://stlpartnership.com/ Serving St. Louis City and County]
* [http://mulibraries.missouri.edu/specialcollections/platbooks.htm Digitized 1930 Plat Book of St. Louis County] {{Webarchive|url=https://web.archive.org/web/20110816173126/http://mulibraries.missouri.edu/specialcollections/platbooks.htm |date=August 16, 2011}} from [[University of Missouri]] Division of Special Collections, Archives, and Rare Books
* {{Cite AmCyc|wstitle=Saint Louis (county) |display=The American Cyclopædia (1879)/Saint Louis (county) |short=x}}

{{Geographic location
|Centre    = St. Louis County, Missouri
|North     = [[St. Charles County, Missouri|St. Charles County]]
|Northeast = [[Madison County, Illinois]]
|East      = [[St. Louis|City of St. Louis]]
|Southeast = [[St. Clair County, Illinois]] and [[Monroe County, Illinois]]
|South     = [[Jefferson County, Missouri|Jefferson County]]
|Southwest = [[Franklin County, Missouri|Franklin County]]
|West      =
|Northwest = [[St. Charles County, Missouri|St. Charles County]]
}}
{{St. Louis MSA}}
{{St. Louis County, Missouri}}
{{Missouri}}
{{Coord|38.64|-90.44|display=title|type:adm2nd_region:US-MO_source:UScensus1990}}

{{Authority control}}

{{DEFAULTSORT:St. Louis County, Missouri}}
[[Category:St. Louis County, Missouri| ]]
[[Category:1812 establishments in Missouri Territory]]
[[Category:Populated places established in 1812]]
[[Category:Missouri counties on the Mississippi River]]
[[Category:Missouri counties on the Missouri River]]
[[Category:Regions of Greater St. Louis]]