View source for New Castle County, Delaware

{{short description|County in Delaware, United States}}
{{Use American English|date=June 2025}}
{{Use mdy dates|date=April 2024}}
{{Infobox U.S. county
 | county    = New Castle County
 | state              = Delaware
 | type                 = [[List of counties in Delaware|County of Delaware]]
 | named for            = [[William Cavendish, 1st Duke of Newcastle]]
 | flag                 = Flag of New Castle County, Delaware.svg
 | seal                 = NewCastleCountySeal.png
 | founded year         = 1673
 | founded date       = August 8
 | seat wl          = Wilmington
 | largest city wl  = Wilmington
 | area_total_sq_mi     = 494
 | area_land_sq_mi      = 426
 | area_water_sq_mi     = 68
 | area percentage      = 13.8
 | census yr            = 2020
 | pop                  = 570719
 | pop_est_as_of        = 2024
 | pop_est_footnotes        =<ref> name="USCensusEst2024"</ref>
 | population_est       = 588093 {{increase}}
 | density_sq_mi        = auto
 | district           = At-large
 | time zone           = Eastern
 | website                = {{URL|https://www.newcastlede.gov|newcastlede.gov}}
 | ex image             = Habs new castle county court house.jpg
 | ex image cap         = [[New Castle Court House Museum|Old New Castle Courthouse]] in New Castle (1936) }}

'''New Castle County''' is the northernmost of the three [[List of counties in Delaware|counties]] of the [[U.S. state]] of [[Delaware]] (New Castle, [[Kent County, Delaware|Kent]], and [[Sussex County, Delaware|Sussex]]). As of the [[2020 United States census|2020 census]], the population was 570,719,<ref name="QF">{{cite web |title=U.S. Census Bureau QuickFacts: New Castle County, Delaware |url=https://www.census.gov/quickfacts/newcastlecountydelaware |publisher=U.S. Census Bureau |access-date=August 24, 2021}}</ref> making it the most populous county in Delaware, with nearly 60% of the state's population of 989,948. The [[county seat]] is [[Wilmington, Delaware|Wilmington]],<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> which is also the state's most populous city. New Castle County is included in the [[Philadelphia]]-[[Camden, New Jersey|Camden]]-[[Wilmington, Delaware|Wilmington]], [[Delaware Valley|PA-NJ-DE-MD Metropolitan Statistical Area]]. The county is named after [[William Cavendish, 1st Duke of Newcastle]] ({{Circa|1593}}–1676).{{Citation needed|date=July 2024}} New Castle County has the highest population and population density of any Delaware county, and it is the smallest county in the state by area. It has more people than the other two counties, [[Kent County, Delaware|Kent]] and [[Sussex County, Delaware|Sussex]], combined. It is also the most economically developed of the three.

==History==
The first permanent European settlement on Delaware soil was [[Fort Christina]], resulting from [[Peter Minuit]]'s 1638 expedition on the Swedish vessels ''[[Fogel Grip]]'' and ''[[Kalmar Nyckel]]''. The Swedes laid out the town at the site of modern-day Wilmington. They contracted with the [[Lenape]] Native Americans for land of Old Cape Henlopen north to Sankikans (Trenton Falls), and inland as far as they desired. However, a dispute ensued between the Swedes and the Dutch, who asserted a prior claim to that land.

In 1640, [[New Sweden]] was founded a few miles south of [[Christina River|Christina]]. In 1644, Queen Christina appointed Lt. Col. [[Johan Printz]] as Governor of [[New Sweden]]. She directed boundaries to be set and to reach [[Cape Henlopen]] north along the west side of Godyn's Bay ([[Delaware Bay]]), up the South River ([[Delaware River]]), past Minquas Kill ([[Christina River]]), to Sankikans (Trenton Falls). Printz settled on [[Tinicum Township, Delaware County, Pennsylvania|Tinicum Island]], as the seat of government and capital of the [[New Sweden]] colony.

[[Peter Stuyvesant]], Governor of [[New Netherland]], sailed up the [[Delaware River|South River]] in 1651. He purchased land from the Lenape that covered Minquas Kill to Bompties Hook ([[Bombay Hook]]); the Lenape had sold part of the property to the Swedes in 1638. Stuyvesant began to build [[Fort Casimir]] (contemporary [[New Castle, Delaware|New Castle]]).

In 1654, [[Johan Risingh]], commissary and councilor to the governor Lt. Col. Printz, officially assumed Printz's duties and began to expel all Dutch from New Sweden. [[Fort Casimir]] surrendered and was renamed Fort Trinity in 1654. The Swedes had complete possession of the west side of the Delaware River. On June 21, 1654, the Lenape met with the Swedes to reaffirm the purchase.

Having learned of the fall of Fort Casimir, the Dutch sent Stuyvesant to drive the Swedes from both sides of the river. They allowed only Dutch colonists to settle in the area and on August 31, 1655, the territory was converted back to Fort Casimir. Consequently, Fort Christina fell on September 15 to the Dutch, was renamed [[Fort Christina|Fort Altena]] and [[New Netherland]] ruled once again. John Paul Jacquet was immediately appointed governor, making [[New Amstel]] the capital of the Dutch-controlled colony.

The [[Dutch West India Company]] conveyed land from the south side of Christina Kill to [[Bombay Hook National Wildlife Refuge|Bombay Hook]], and as far west as Minquas land. This land was known as the Colony of The city. On December 22, 1663, the Dutch transferred property rights to the territory along the Delaware River to England.

In 1664, the [[James II of England|duke of York, James]], was granted this land by [[Charles II of England|King Charles II]]. One of the first acts by the Duke was to order removal of all Dutch from [[New Amsterdam]]; he renamed [[New Amstel]] as New Castle. In 1672, the town of New Castle was incorporated and English law ordered. However, in 1673, the Dutch attacked the territory, reclaiming it for their own.

On September 12, 1673, the Dutch established [[New Amstel]] in present-day [[Delaware]], fairly coterminous with today's New Castle County. The establishment was not stable, and it was transferred to the British under the [[Treaty of Westminster (1674)|Treaty of Westminster]] on February 9, 1674. On November 6, 1674, New Amstel was made dependent on New York Colony, and was renamed New Castle on November 11, 1674.

On September 22, 1676, New Castle County was formally placed under the Duke of York's laws. It gained land from [[Upland County]] on November 12, 1678.

On June 21, 1680, [[St. Jones County]] was carved from New Castle County. It is known today as [[Kent County, Delaware]]. On August 24, 1682, New Castle County, along with the rest of the surrounding land, was transferred from the Colony of New York to the possession of [[William Penn]], who established the Colony of Delaware.<ref>''New York: Atlas of Historical County Boundaries'' by Kathryn Ford Thorne and John H. Long</ref>

In September 1673, a Dutch council established a court at New Castle with the boundaries defined as north of Steen Kill (present-day Stoney Creek) and south to Bomties Hook (renamed Bombay Hook). In 1681, a [[The Twelve-Mile Circle|12-mile arc]] was drawn to specifically delineate the northern border of New Castle County as it currently exists. In 1685, the western border was finally established by King James II; this was set as a line from Old Cape Henlopen (presently [[Fenwick Island, Delaware|Fenwick]]) west to the middle of the peninsula and north up to the middle of the peninsula to the 40th parallel.<ref>{{Cite web |url=http://www.co.new-castle.de.us/Council/Countyhistory.htm |title=A Brief History of New Castle County, Delaware |access-date=May 28, 2005 |archive-url=https://web.archive.org/web/20050408053852/http://www.co.new-castle.de.us/Council/Countyhistory.htm |archive-date=April 8, 2005 |url-status=dead }}</ref>

==Geography==
[[File:Chesapeake and Delaware Canal eastern entrance.jpg|thumb|right|Chesapeake and Delaware Canal]]
According to the [[United States Census Bureau|U.S. Census Bureau]], the county has a total area of {{convert|494|sqmi}}, of which {{convert|426|sqmi}} is land and {{convert|68|sqmi}} (13.8%) is water.<ref name="GR1">{{cite web|url=https://www.census.gov/geographies/reference-files/time-series/geo/gazetteer-files.html|publisher=[[United States Census Bureau]]|access-date=April 23, 2011|date=February 12, 2011|title=US Gazetteer files: 2010, 2000, and 1990}}</ref> The boundaries of New Castle County are described in § 102 of the Delaware Code.<ref name=DelCode102>{{Cite web| title=Delaware Code, Title 9| url=https://delcode.delaware.gov/title9/c001/index.html| date=October 31, 2008| publisher=State of Delaware| access-date=November 22, 2008}}</ref> The county is drained by [[Brandywine Creek (Christina River)|Brandywine Creek]], [[Christina River]], and other channels.<ref>{{Cite AmCyc|wstitle=New Castle (Delaware)|display=New Castle, a N. county of Delaware}}</ref> Its eastern edge sits along the [[Delaware River]] and [[Delaware Bay]].

Two small [[exclave]]s of the county and the state lie across the Delaware River, on its east bank on the [[New Jersey]] side, [[Finns Point]]  adjacent to [[Pennsville Township, New Jersey]], and the northern tip of [[Artificial Island, New Jersey|Artificial Island]], adjacent to [[Lower Alloways Creek Township, New Jersey]].<ref>Schoonejongen, John. [http://blogs.app.com/capitolquickies/2010/09/10/how-delaware-got-on-jerseys-side-of-the-river/ "How Delaware got on Jersey’s side of the river"], ''[[Asbury Park Press]]'', September 10, 2010. Accessed September 21, 2015. "Killcohook, in Pennsville Township, is another. Not only is it a 'confined disposal facility' for dredging materials, Killcohook is also the name of a nearby wildlife refuge. It borders another wildlife refuge, Supawna, as well as the Finns Point National Cemetery, the Finns Point Lighthouse and Fort Mott State Park."</ref>

New Castle County, like all of Delaware's counties, is subdivided into [[Hundred (county subdivision)|hundreds]]. New Castle County is apportioned into eleven hundreds: Brandywine, Christiana, Wilmington (the city of Wilmington, which, by law, is a hundred in itself), Mill Creek, White Clay Creek, Pencader, New Castle, Red Lion, St. Georges, Appoquinimink, and Blackbird.

[[Ebright Azimuth]], the highest natural point in Delaware at {{convert|448|ft|m}}, is located in New Castle County.

The [[Chesapeake and Delaware Canal]] was built through New Castle County, and adjoining Cecil County, Maryland, between 1822 and 1829.

===Adjacent counties===
* [[Chester County, Pennsylvania]] – northwest
* [[Delaware County, Pennsylvania]] – north
* [[Gloucester County, New Jersey]] – northeast
* [[Salem County, New Jersey]] – east
* [[Kent County, Delaware]] – south
* [[Kent County, Maryland]] – southwest
* [[Cecil County, Maryland]] – west

===Major roads and highways===
[[File:2022-07-20 13 56 33 View south along Interstate 95 (Delaware Turnpike) from the overpass for the ramp to southbound Delaware State Route 1 and Delaware State Route 7 (Korean War Veterans Memorial Highway) in Christiana, New Castle County, Delaware.jpg|thumb|right|I-95/Delaware Turnpike southbound in New Castle County]]
{{div col|colwidth=22em}}
* {{jct|state=DE|I|95|DETP}}
* {{jct|state=DE|I|295}}
* {{jct|state=DE|I|495}}
* {{jct|state=DE|US|13}}
* {{jct|state=DE|US-Bus|13|dab1=Wilmington}}
* {{jct|state=DE|US|40}}
* {{jct|state=DE|US|202}}
* {{jct|state=DE|US|301}}
* {{jct|state=DE|DE|1}}
* {{jct|state=DE|DE|2}}
* {{jct|state=DE|DE|3}}
* {{jct|state=DE|DE|4}}
* {{jct|state=DE|DE|7}}
* {{jct|state=DE|DE|9}}
* {{jct|state=DE|DE|9A}}
* {{jct|state=DE|DE|15}}
* {{jct|state=DE|DE|37}}
* {{jct|state=DE|DE|41}}
* {{jct|state=DE|DE|48}}
* {{jct|state=DE|DE|52}}
* {{jct|state=DE|DE|58}}
* {{jct|state=DE|DE|62}}
* {{jct|state=DE|DE|71}}
* {{jct|state=DE|DE|72}}
* {{jct|state=DE|DE|82}}
* {{jct|state=DE|DE|92}}
* {{jct|state=DE|DE|100}}
* {{jct|state=DE|DE|141}}
* {{jct|state=DE|DE|202}}
* {{jct|state=DE|DE|261}}
* {{jct|state=DE|DE|273}}
* {{jct|state=DE|DE|279}}
* {{jct|state=DE|DE|286}}
* {{jct|state=DE|DE|299}}
* {{jct|state=DE|DE|491}}
* {{jct|state=DE|DE|896}}
{{div col end}}

===Climate===
Almost all of the county has a [[humid subtropical climate]] (''Cfa'') except for the highest area around [[Ebright Azimuth]] where the climate is hot-summer [[humid continental climate|humid continental]] (''Dfa''.) The [[hardiness zone]] is 7b except in some higher areas close to the Pennsylvania border which are 7a.

{{Weather box
|location = Wilmington, Delaware ([[New Castle County Airport]]), 1981–2010 normals, extremes 1894–present
|single line = Y
|Jan record high F =  75
|Feb record high F =  78
|Mar record high F =  86
|Apr record high F =  97
|May record high F =  98
|Jun record high F = 102
|Jul record high F = 106
|Aug record high F = 107
|Sep record high F = 100
|Oct record high F =  98
|Nov record high F =  85
|Dec record high F =  75

|Jan avg record high F =61.2
|Feb avg record high F =63.1
|Mar avg record high F =73.7
|Apr avg record high F =82.6
|May avg record high F =88.3
|Jun avg record high F =93.2
|Jul avg record high F =96.0
|Aug avg record high F =93.7
|Sep avg record high F =89.1
|Oct avg record high F =81.6
|Nov avg record high F =72.5
|Dec avg record high F =63.9
|year avg record high F=96.9
|Jan high F = 40.2
|Feb high F = 43.5
|Mar high F = 52.4
|Apr high F = 63.5
|May high F = 73.0
|Jun high F = 81.8
|Jul high F = 86.1
|Aug high F = 84.2
|Sep high F = 77.4
|Oct high F = 66.2
|Nov high F = 55.7
|Dec high F = 44.6
|year high F =64.1
|Jan low F = 24.6
|Feb low F = 26.8
|Mar low F = 33.6
|Apr low F = 43.0
|May low F = 52.6
|Jun low F = 62.6
|Jul low F = 67.6
|Aug low F = 66.1
|Sep low F = 58.2
|Oct low F = 46.1
|Nov low F = 37.4
|Dec low F = 28.7
|year low F =45.7
|Jan avg record low F =  7.4
|Feb avg record low F = 11.6
|Mar avg record low F = 17.9
|Apr avg record low F = 29.7
|May avg record low F = 38.7
|Jun avg record low F = 49.9
|Jul avg record low F = 56.7
|Aug avg record low F = 54.3
|Sep avg record low F = 43.7
|Oct avg record low F = 32.8
|Nov avg record low F = 23.3
|Dec avg record low F = 13.6
|year avg record low F=  4.3
|Jan record low F = −14
|Feb record low F = −15
|Mar record low F =   2
|Apr record low F =  11
|May record low F =  30
|Jun record low F =  40
|Jul record low F =  48
|Aug record low F =  43
|Sep record low F =  32
|Oct record low F =  23
|Nov record low F =  11
|Dec record low F =  −7
|precipitation colour = green
|Jan precipitation inch = 3.01
|Feb precipitation inch = 2.68
|Mar precipitation inch = 3.92
|Apr precipitation inch = 3.50
|May precipitation inch = 3.95
|Jun precipitation inch = 3.88
|Jul precipitation inch = 4.57
|Aug precipitation inch = 3.25
|Sep precipitation inch = 4.32
|Oct precipitation inch = 3.42
|Nov precipitation inch = 3.10
|Dec precipitation inch = 3.48
|year precipitation inch=43.08
|Jul snow inch = 0
|Aug snow inch = 0
|Sep snow inch = 0
|Oct snow inch = 0
|Nov snow inch = 0.4
|Dec snow inch = 3.4
|Jan snow inch = 5.9
|Feb snow inch = 8.3
|Mar snow inch = 1.9
|Apr snow inch = 0.3
|May snow inch = 0
|Jun snow inch = 0
|year snow inch=20.2
|unit precipitation days = 0.01 in
|Jan precipitation days = 10.5
|Feb precipitation days = 9.4
|Mar precipitation days = 10.7
|Apr precipitation days = 11.3
|May precipitation days = 11.2
|Jun precipitation days = 10.3
|Jul precipitation days = 9.9
|Aug precipitation days = 8.1
|Sep precipitation days = 8.5
|Oct precipitation days = 8.3
|Nov precipitation days = 9.2
|Dec precipitation days = 10.3
|year precipitation days=117.7
|unit snow days = 0.1 in
|Jul snow days = 0
|Aug snow days = 0
|Sep snow days = 0
|Oct snow days = 0
|Nov snow days = 0.2
|Dec snow days = 2.0
|Jan snow days = 4.3
|Feb snow days = 3.6
|Mar snow days = 1.3
|Apr snow days = 0.4
|May snow days = 0
|Jun snow days = 0
|year snow days=11.8
|source = NOAA<ref name= "NOWData NWS Mount Holly, NJ">{{cite web |url=http://w2.weather.gov/climate/xmacis.php?wfo=phi |title=NowData: NOAA Online Weather Data |publisher=[[National Oceanic and Atmospheric Administration]] |access-date=October 3, 2019 |archive-url=https://web.archive.org/web/20181130075334/http://w2.weather.gov/climate/xmacis.php?wfo=phi |archive-date=November 30, 2018 |url-status=live }}</ref><ref name="NCDC txt KILG">{{cite web |url=ftp://ftp.ncdc.noaa.gov/pub/data/normals/1981-2010/products/station/USW00013781.normals.txt |publisher=National Oceanic and Atmospheric Administration |archive-url=https://web.archive.org/web/20200724003343/ftp://ftp.ncdc.noaa.gov/pub/data/normals/1981-2010/products/station/USW00013781.normals.txt |archive-date=2020-07-24 |url-status=dead |title=Station Name: DE WILMINGTON NEW CASTLE CO AP |access-date=October 3, 2019 }}</ref>
}}

==Demographics==
{{US Census population
|1790= 19688
|1800= 25361
|1810= 24429
|1820= 27899
|1830= 29720
|1840= 33120
|1850= 42780
|1860= 54797
|1870= 63515
|1880= 77716
|1890= 97182
|1900= 109697
|1910= 123188
|1920= 148239
|1930= 161032
|1940= 179562
|1950= 218879
|1960= 307446
|1970= 385856
|1980= 398115
|1990= 441946
|2000= 500265
|2010= 538479
|2020= 570719
|estyear=2024
|estimate=588093
|estref=<ref name="USCensusEst2024">{{cite web|url=https://www.census.gov/programs-surveys/popest/data/tables.html|title=Annual Estimates of the Resident Population for Counties: April 1, 2020 to July 1, 2024|publisher=United States Census Bureau|access-date=March 27, 2025}}</ref>
|align-fn=center
|footnote=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=June 12, 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=June 12, 2014}}</ref> 1900-1990<ref>{{cite web|url=https://www.census.gov/population/cencounts/de190090.txt|title=Population of Counties by Decennial Census: 1900 to 1990|publisher=United States Census Bureau|access-date=June 12, 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://ghostarchive.org/archive/20221009/https://www.census.gov/population/www/cen2000/briefs/phc-t4/tables/tab02.pdf |archive-date=October 9, 2022 |url-status=live|title=Census 2000 PHC-T-4. Ranking Tables for Counties: 1990 and 2000|publisher=United States Census Bureau|access-date=June 12, 2014}}</ref> 2010-2020<ref name="QF" />
}}
[[File:Hindu Temple Delaware Pic -2.jpg|thumb|[[Hindu Temple of Delaware]]]]
[[File:St Anthony of Padua church 2.jpg|thumb|[[St. Anthony's Roman Catholic Church (Wilmington, Delaware)|St. Anthony of Padua Roman Catholic Church]]]]

=== 2020 census ===
{| class="wikitable" style="text-align:center;"
|+'''New Castle County, Delaware – 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>
!Race / Ethnicity <small>(''NH = Non-Hispanic'')</small>
!Pop 2000<ref name=2000CensusP004>{{Cite web|title=P004: Hispanic or Latino, and Not Hispanic or Latino by Race – 2000: DEC Summary File 1 – New Castle County, Delaware |url=https://data.census.gov/table?g=050XX00US10003&tid=DECENNIALSF12000.P004|website=[[United States Census Bureau]] |access-date= }}</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) – New Castle County, Delaware |url=https://data.census.gov/cedsci/table?q=p2&g=050XX00US10003&tid=DECENNIALPL2010.P2|website=[[United States Census Bureau]] |access-date= }}</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) – New Castle County, Delaware|url=https://data.census.gov/cedsci/table?q=p2&g=050XX00US10003&tid=DECENNIALPL2020.P2|website=[[United States Census Bureau]] |access-date= }}</ref>
!% 2000
!% 2010
!{{partial|% 2020}}
|-
|[[Non-Hispanic or Latino whites|White]] alone (NH)
|353,760
|331,836
|style='background: #ffffe6; |303,265
|70.71%
|61.62%
|style='background: #ffffe6; |53.14%
|-
|[[Non-Hispanic or Latino African Americans|Black or African American]] alone (NH)
|99,648
|124,426
|style='background: #ffffe6; |142,388
|19.92%
|23.11%
|style='background: #ffffe6; |24.95%
|-
|[[Native Americans in the United States|Native American]] or [[Alaska Native]] alone (NH)
|806
|984
|style='background: #ffffe6; |893
|0.16%
|0.18%
|style='background: #ffffe6; |0.16%
|-
|[[Asian Americans|Asian]] alone (NH)
|12,856
|23,132
|style='background: #ffffe6; |35,022
|2.57%
|4.30%
|style='background: #ffffe6; |6.14%
|-
|[[Native Hawaiian]] or [[Pacific Islander Americans|Pacific Islander]] alone (NH)
|139
|102
|style='background: #ffffe6; |127
|0.03%
|0.02%
|style='background: #ffffe6; |0.02%
|-
|[[Race and ethnicity in the United States census|Other race]] alone (NH)
|631
|873
|style='background: #ffffe6; |2,555
|0.13%
|0.16%
|style='background: #ffffe6; |0.45%
|-
|[[Multiracial Americans|Mixed race or Multiracial]] (NH)
|6,132
|10,205
|style='background: #ffffe6; |22,953
|1.23%
|1.90%
|style='background: #ffffe6; |4.02%
|-
|[[Hispanic and Latino Americans|Hispanic or Latino]] (any race)
|26,293
|46,921
|style='background: #ffffe6; |63,516
|5.26%
|8.71%
|style='background: #ffffe6; |11.13%
|-
|'''Total'''
|'''500,265'''
|'''538,479'''
|style='background: #ffffe6; |'''570,719'''
|'''100.00%'''
|'''100.00%'''
|style='background: #ffffe6; |'''100.00%'''
|}

As of the [[2020 United States census|2020 census]], there were 570,719 people living in the county. The racial and ethnic makeup (where Latinos are treated as if a separate racial group) shows that the county was 53.1% non-Hispanic white, 25.0% non-Hispanic African American, 0.2% non-Hispanic Native American, 6.1% non-Hispanic Asian, 0.02% non-Hispanic Pacific Islander, 4.0% non-Hispanic multiracial, and 11.1% Hispanic or Latino of any race. The most reported ancestries were:<ref>{{cite web |title=TOTAL POPULATION |url=https://data.census.gov/table?t=-06:-1000E:-3000F:-4000G:-5000K:-7000E:-8000B&g=050XX00US10003&d=DEC+Detailed+Demographic+and+Housing+Characteristics+File+A |website=data.census.gov |publisher=U.S. Census Bureau}}</ref>
* [[Irish people|Irish]] (17.2%)
* [[African Americans|African American]] (15.6%)
* [[English people|English]] (12.8%)
* [[Germans|German]] (12.8%)
* [[Italians|Italian]] (10.2%)
* [[Polish people|Polish]] (4.7%)
* [[Mexicans|Mexican]] (4.4%)
* [[Puerto Ricans|Puerto Rican]] (3.6%)
* [[Indian people|Indian]] (3%)
* [[Scottish people|Scottish]] (2.7%)

===2010 census===
As of the [[2010 United States Census|2010 census]], there were 538,479 people, 202,651 households, and 134,743 families residing in the county.<ref name="census-dp1">{{cite web
  |url=http://factfinder.census.gov/bkmk/table/1.0/en/DEC/10_DP/DPDP1/0500000US10003
  |title=DP-1 Profile of General Population and Housing Characteristics: 2010 Demographic Profile Data
  |access-date=January 12, 2016
|publisher=[[United States Census Bureau]]
  |archive-url=https://archive.today/20200213011828/http://factfinder.census.gov/bkmk/table/1.0/en/DEC/10_DP/DPDP1/0500000US10003
  |archive-date=February 13, 2020
|url-status=dead
}}</ref> The population density was {{convert|1,263.2|PD/sqmi}}. There were 217,511 housing units at an average density of {{convert|510.2|/sqmi}}.<ref name="census-density">{{cite web
  |url=http://factfinder.census.gov/bkmk/table/1.0/en/DEC/10_SF1/GCTPH1.CY07/0500000US10003
  |access-date=January 12, 2016
|title=Population, Housing Units, Area, and Density: 2010 – County
  |publisher=[[United States Census Bureau]]
  |archive-url=https://archive.today/20200213162025/http://factfinder.census.gov/bkmk/table/1.0/en/DEC/10_SF1/GCTPH1.CY07/0500000US10003
  |archive-date=February 13, 2020
|url-status=dead
  }}</ref> The racial makeup of the county was 65.5% white, 23.7% black or African American, 4.3% Asian, 0.3% American Indian, 3.5% from other races, and 2.5% from two or more races. Those of Hispanic or Latino origin made up 8.7% of the population.<ref name="census-dp1"/> In terms of ancestry, 19.2% were [[Irish people|Irish]], 15.0% were [[Germans|German]], 11.7% were [[Italians|Italian]], 11.3% were [[English people|English]], 6.2% were [[Polish people|Polish]], and 3.0% were [[Americans|American]].<ref name="census-dp2">{{cite web
  |url=http://factfinder.census.gov/bkmk/table/1.0/en/ACS/10_5YR/DP02/0500000US10003
  |title=DP02 SELECTED SOCIAL CHARACTERISTICS IN THE UNITED STATES – 2006-2010 American Community Survey 5-Year Estimates
  |access-date=January 12, 2016
|publisher=[[United States Census Bureau]]
  |archive-url=https://archive.today/20200213013959/http://factfinder.census.gov/bkmk/table/1.0/en/ACS/10_5YR/DP02/0500000US10003
  |archive-date=February 13, 2020
|url-status=dead
}}</ref>

Of the 202,651 households, 33.8% had children under the age of 18 living with them, 46.6% were married couples living together, 14.9% had a female householder with no husband present, 33.5% were non-families, and 26.1% of all households were made up of individuals. The average household size was 2.57 and the average family size was 3.11. The median age was 37.2 years.<ref name="census-dp1"/>

The median income for a household in the county was $62,474 and the median income for a family was $78,072. Males had a median income of $52,637 versus $41,693 for females. The per capita income for the county was $31,220. About 6.6% of families and 10.3% of the population were below the [[poverty line]], including 13.6% of those under age 18 and 7.6% of those age 65 or over.<ref name="census-dp3">{{cite web
  |url=http://factfinder.census.gov/bkmk/table/1.0/en/ACS/10_5YR/DP03/0500000US10003
  |title=DP03 SELECTED ECONOMIC CHARACTERISTICS – 2006-2010 American Community Survey 5-Year Estimates
  |access-date=January 12, 2016
|publisher=[[United States Census Bureau]]
  |archive-url=https://archive.today/20200213034758/http://factfinder.census.gov/bkmk/table/1.0/en/ACS/10_5YR/DP03/0500000US10003
  |archive-date=February 13, 2020
|url-status=dead
}}</ref>

===2000 census===
As of the [[census]] of 2000, there were 500,265 people, 188,935 households, and 127,153 families residing in the county. The population density was {{convert|1,174|PD/sqmi|PD/km2|sp=us|adj=off}}. There were 199,521 housing units at an average density of {{convert|468|/sqmi|/km2|sp=us|adj=off}}. The racial makeup of the county was 73.12% [[Race (United States Census)|White]], 20.22% [[Race (United States Census)|Black]] or [[Race (United States Census)|African American]], 0.20% [[Race (United States Census)|Native American]], 2.59% [[Race (United States Census)|Asian]], 0.03% [[Race (United States Census)|Pacific Islander]], 2.22% from [[Race (United States Census)|other races]], and 1.62% from two or more races. 5.26% of the population were [[Race (United States Census)|Hispanic]] or [[Race (United States Census)|Latino]] of any race. 14.6% were of [[Irish people|Irish]], 11.4% [[Italian people|Italian]], 10.9% [[German people|German]], 8.8% [[English people|English]] and 5.4% [[Polish people|Polish]] ancestry. 89.5% spoke [[English language|English]] and 5.3% [[Spanish language|Spanish]] as their first language.

There were 188,935 households, out of which 32.50% had children under the age of 18 living with them, 49.60% were [[Marriage|married couples]] living together, 13.40% had a female householder with no husband present, and 32.70% were non-families. 25.70% of all households were made up of individuals, and 8.50% had someone living alone who was 65 years of age or older. The average household size was 2.56 and the average family size was 3.09.

In the county, the population was spread out, with 24.90% under the age of 18, 10.30% from 18 to 24, 31.50% from 25 to 44, 21.70% from 45 to 64, and 11.60% who were 65 years of age or older. The median age was 35 years. For every 100 females there were 94.40 males. For every 100 females age 18 and over, there were 90.80 males.

The median income for a household in the county was $52,419, and the median income for a family was $62,144. Males had a median income of $42,541 versus $31,829 for females. The [[per capita income]] for the county was $25,413. 8.40% of the population and 5.60% of families were below the [[poverty line]]. Out of the total population, 10.20% of those under the age of 18 and 7.40% of those 65 and older were living below the poverty line.

==Government==
===County government===

====County executive====
The county is headed by a [[county executive]], currently Marcus Henry. The chief administrative officer, who is the county's second-in-command, is appointed by the county executive and serves at his or her pleasure. Mona Parikh was appointed CAO in January 2025.<ref>{{Cite web|date=March 7, 2018|title=New Castle County names Vanessa Phillips as chief administrative officer|url=https://delawarebusinesstimes.com/news/new-castle-county-names-vanessa-phillips-chief-administrative-officer/|access-date=October 20, 2020|website=Delaware Business Times|language=en-US}}</ref>

====County offices====
The New Castle County government maintains the New Castle County Government Center in an unincorporated area; it has a New Castle postal address.<ref>{{cite web|url=https://www.newcastlede.gov/|title=Home|publisher=New Castle County|access-date=2025-03-30|quote=New Castle County Government Center 87 Read’s Way New Castle, DE 19720}} - Compare to: {{cite map|author=Geography Division|url=https://www2.census.gov/geo/maps/DC2020/DC20BLK/st10_de/county/c10003_new_castle/DC20BLK_C10003.pdf|title=2020 CENSUS - CENSUS BLOCK MAP (INDEX): New Castle County, DE|publisher=[[U.S. Census Bureau]]|date=April 12, 2021|page=12 (PDF p. 13/45)|accessdate=2021-06-30}} - White means an unincorporated area</ref> The facility opened in May 1997 after it acquired the facility from [[Wilmington Trust]]. Previously these county offices were at the Louis L. Redding City/County Building, with some others in the County Engineering Building. The latter building is no longer in use. By 1998 the majority of the county employees were based at the Government Center.<ref>{{cite news|last=Thompson|first=Dennis, Jr.|title=NCCo Center too secure, some charge|newspaper=[[The News Journal]]|date=1998-07-05|pages=[https://www.newspapers.com/clip/169236592/ B1]-[https://www.newspapers.com/clip/169236693/ B2]|via=[[Newspapers.com]]}}</ref>

The Redding Building was built in 1976.<ref>{{cite web|url=https://www.wilmingtondewater.gov/facilities/facility/details/City-County-Building-1|title=City / County Building|publisher=Wilmington Water Utility (.gov)|access-date=2025-03-30}}</ref> The city/county council chambers are at Redding.<ref>{{cite web|url=https://www.newcastlede.gov/AgendaCenter/ViewFile/ArchivedAgenda/_07232019-1312|title=NEW CASTLE COUNTY COUNCIL Louis L. Redding City/County Building City/County Council Chambers 800 French Street, Wilmington, DE 19801 July 23, 2019|publisher=New Castle County|access-date=2025-03-30}}</ref>

====County Council====
{{anchor|New Castle County Council}}
The county's legislative body is a thirteen-member [[county council]], consisting of twelve members elected by district and one president elected at large.<ref>{{Cite web|title=Members {{!}} New Castle County, DE - Official Website|url=https://www.nccde.org/421/Members|access-date=July 18, 2020|website=www.nccde.org}}</ref> The council is tasked with drafting laws and managing county government services, [[public health]] ordinances, [[land use]], transportation, and [[zoning]].<ref>{{Cite web|title=County Council {{!}} New Castle County, DE - Official Website|url=https://nccde.org/226/County-Council|access-date=July 18, 2020|website=nccde.org}}</ref><ref>{{Cite web | title=Our Campaigns - United States - Delaware - DE Counties - New Castle - County Council| url= https://www.ourcampaigns.com/ContainerDetail.html?ContainerID=29261| access-date=July 18, 2020|website=www.ourcampaigns.com}}</ref><ref>{{Cite news | last=Milford| first=Maureen| date=April 8, 1990| title=National Notebook: Middleton, Del.; Annexing Farmland| language=en-US| work=The New York Times| url=https://www.nytimes.com/1990/04/08/realestate/national-notebook-middletown-del-annexing-farmland.html |access-date=July 18, 2020| issn=0362-4331}}</ref>  New Castle County Council doubled in size to thirteen from seven members in 2004. Its most famous council member was [[Joe Biden]], the 46th [[president of the United States]], who represented the 4th district from 1971 to 1973.<ref>{{Cite news | last=Harriman| first=Jane| url=http://www.newspapers.com/image/?clipping_id=8326887| title=Joe Biden: Hope for Democratic Party in '72?| date=December 31, 1969| access-date=October 19, 2020| publisher=The News Journal| page=3| language=en| website=Newspapers.com}}</ref>

Current county council members are:<ref>{{Cite web | title=County Council {{!}} New Castle County, DE - Official Website| url=https://nccde.org/226/County-Council| url-status=live| archive-url=https://web.archive.org/web/20201020004655/https://nccde.org/226/County-Council| archive-date=October 20, 2020| access-date=October 20, 2020| website=nccde.org}}</ref>
* District 1: Brandon Toole (D)
* District 2: Dee Durham (D)
* District 3: Janet Kilpatrick (D)
* District 4: Penrose Hollins (D)
* District 5: Valerie George (D)
* District 6: David Carter (D)
* District 7: George Smiley (D)
* District 8: John J. Cartier (D)
* District 9: Timothy P. Sheldon (D)
* District 10: Jea P. Street (D)
* District 11: David L. Tackett (D)
* District 12: Kevin Caneco (D)
* At Large: Karen Hartley-Nagle (D), President

====County judiciary====
As with Delaware's other two counties, New Castle County has no judiciary of its own. All judicial functions, except for Alderman's Courts, are managed and funded by the state of [[Delaware]]. In New Castle County, only the cities of Newport and Newark have alderman's courts. These courts have jurisdiction over driving offenses, misdemeanor criminal charges, and minor civil claims.

====County row offices====
The county retains the concept of "row offices" from Pennsylvania, so-called because all of these county offices could be found in a row in smaller courthouses. In Delaware, these offices are [[Clerk of the Peace|clerk of the peace]], [[Recorder of Deeds|recorder of deeds]], register of wills, and [[sheriff]].

The office of clerk of the peace is unique among the 50 states; the office-holder's function is almost exclusively to perform marriages. The current incumbent is Kenneth W. Boulden Jr. (D)

The [[Recorder of Deeds|recorder of deeds]] is Michael Kozikowski (D). His office is responsible for receiving and recording [[deed]]s, [[mortgage law|mortgages]] and satisfactions thereof, assignments, commissions of [[judge]]s, [[notary public|notaries]], and military officers. The recorder of deeds' office is heavily computerized; electronic images of all recent documents and many others are available the office is in the process of imaging further back with the eventual goal of all documents in the office's possession being available electronically. Computerized indexing and searching is also available.<ref>{{cite web |url=http://www.ncc-deeds.com/ |title=New Castle County Recorder of Deeds Public Web Access |publisher=Ncc-deeds.com |date=May 1, 2007 |access-date=August 20, 2011 |archive-date=May 16, 2008 |archive-url=https://web.archive.org/web/20080516050330/http://www.ncc-deeds.com/ |url-status=dead }}</ref>

The register of wills is Ciro Poppiti, III. His office receives and records [[will (law)|will]]s and small-estate affidavits upon an individual's death, and issues [[letters of administration]] to estate [[executor]]s.

The [[sheriff]] of New Castle County has two divisions, criminal and civil. The criminal division is based in the New Castle County Courthouse in Wilmington. The deputies assigned to this division organize and manage [[Mittimusses|capias]] returns. They also transport prisoners for Superior Court, Court of Common Pleas, and Family Court. The civil division serves legal process, performs levies & impounds and sells property in satisfaction of [[Judgment (law)|judgment]]s. The civil division also locates and apprehends individuals wanted for civil capias. The current sheriff is Scott T. Phillips.

====County zoning and public works====
New Castle County has a strong [[zoning]] code, known as the Unified Development Code, or UDC. The UDC was developed by the Gordon Administration in response to public perception of over- and misdevelopment in the county. New building projects must go through a process of application and approval before construction is permitted to begin.

By operation of state law, New Castle County has no responsibility whatsoever for maintenance of [[roadway]]s. Public roadways are maintained exclusively by the Delaware Department of Transportation, while roadways within neighborhoods and developments are, pursuant to County code, maintained by homeowners' or neighborhood associations.

The Department of Public Works maintains essential infrastructure elements such as sanitary sewers and drainage ways. It also maintains County-owned parks and buildings such as County libraries. It does not maintain the water distribution system, which is owned and operated by several private companies. In general, it also does not maintain stormwater management facilities within subdivisions.

====County public safety====
Access to [[9-1-1|911 emergency services]] is provided by New Castle County through their emergency communications center for all fire/rescue/emergency medical services (EMS) throughout the county and the majority of police services, though Newark, Wilmington, and the University of Delaware maintain their own police emergency call centers. New Castle County has its own nationally accredited police department. The [[New Castle County Police Department]] is the second largest police organization in the state of Delaware. New Castle County maintains a county wide police force with authorization to enforce laws throughout the county, including within incorporated municipalities. The county police force is supported by local municipality police agencies in [[Middletown, Delaware|Middletown]], [[Newark, Delaware|Newark]], [[Delaware City]], [[Wilmington, Delaware|Wilmington]], [[Newport, Delaware|Newport]], [[Elsmere, Delaware|Elsmere]], the city of [[New Castle, Delaware|New Castle]], the [[University of Delaware]], as well as the [[Delaware State Police]].

New Castle County also operates a nationally accredited, county-run paramedic service through its [http://ems.newcastlede.gov Emergency Medical Services Division]. NCC*EMS is the advanced life support (ALS) component of a two-tiered, paramedic intercept EMS system. County paramedics are located in eight full-time stations and one part-time station that operates during the hours of 7:00&nbsp;a.m. to 7:00&nbsp;p.m., with a capability of calling in additional personnel during major emergencies or planned events. Basic life support (BLS) ambulance service is provided primarily by volunteer fire companies with the use of paid employees that are trained in fire suppression and EMS. Fire/Rescue protection is provided by twenty-one volunteer [[Fire Departments in Delaware|fire departments]] throughout the county. The city of Wilmington has its own career municipal fire department and contracts with a private ambulance service for basic life support coverage. The contracted private ambulance service in Wilmington operates in a tiered response configuration with the New Castle County Paramedics.

The Paul J. Sweeney Public Safety Building, located in [[Minquadale]] off of [[U.S. Route 13 in Delaware#New Castle County|US 13]], houses the New Castle County Police and Emergency Medical Services Division Headquarters and the emergency communications center supporting 9-1-1 services.<ref name=taylor2012newsjournal>{{Citation |last=Taylor |first=Adam |date=May 5, 2012
|title=Poor air conditioning jeopardizes 911 calls |newspaper=[[The News Journal]]
 |url=http://www.delawareonline.com/article/20120505/NEWS/205050310/Poor-air-conditioning-jeopardizes-911-calls
 |access-date=May 5, 2012
}}</ref>  The present building opened in 2007 with a construction cost of {{currency|50 million}}.<ref name=taylor2012newsjournal/>  The Headquarters occupied a former [[elementary school]] building on the same site prior to erection of the current building.<ref name=taylor2012newsjournal/>

===Federal government===
New Castle is a strongly Democratic county. Because its population is almost double the combined population of Kent and Sussex, the winner in New Castle County has also won Delaware overall in each of the last eighteen presidential elections. In 1992, 2000, 2004 and 2016, the Republican candidate carried Kent and Sussex, only to lose New Castle by double digits–enough of a margin to swing the entire state to the Democrats. New Castle was a bellwether from 1936 to 1996, as it backed the national winner in every presidential election. It became the longest-running national bellwether after 1996, when [[Okanogan County, Washington]], voted for [[Bob Dole]]. In 2000, [[Valencia County, New Mexico]] became the longest presidential bellwether.

Former governor [[Ronald Reagan]] won the county by just one vote over President [[Jimmy Carter]] in 1980. The county was won by the Republican presidential candidate from 1980 through 1988. This changed when Bill Clinton won the county in 1992 and, like many urban counties, New Castle stayed Democratic ever since.
{{PresHead|place=New Castle County, Delaware|source1=<ref>{{cite web|title = Dave Leip's Atlas of United States Presidential Elections | access-date = November 10, 2024 | url = http://uselectionatlas.org/RESULTS/}}</ref><ref>{{cite web|url=https://www.ourcampaigns.com/ContainerHistory.html?ContainerID=191|title=Our Campaigns|access-date=June 22, 2025}}</ref>}} The county warmly supported former senator and Wilmington resident [[Joe Biden]] as [[Barack Obama]]'s running mate in 2008 and 2012, and during his own bid for president in 2020, each time with well over 65 percent of the vote–more than enough to carry Delaware.
<!-- PresRow should be {{PresRow|Year|Winning party|GOP vote #|Dem vote #|3rd party vote #|State}} -->
{{PresRow|2024|Democratic|90,868|180,700|5,291|Delaware}}
{{PresRow|2020|Democratic|88,364|195,034|4,235|Delaware}}
{{PresRow|2016|Democratic|85,525|162,919|14,535|Delaware}}
{{PresRow|2012|Democratic|81,230|167,082|3,700|Delaware}}
{{PresRow|2008|Democratic|74,608|178,768|3,245|Delaware}}
{{PresRow|2004|Democratic|93,079|146,179|2,269|Delaware}}
{{PresRow|2000|Democratic|78,587|127,539|6,934|Delaware}}
{{PresRow|1996|Democratic|60,943|98,837|19,766|Delaware}}
{{PresRow|1992|Democratic|66,311|91,516|38,990|Delaware}}
{{PresRow|1988|Republican|92,587|79,147|1,269|Delaware}}
{{PresRow|1984|Republican|102,322|76,238|517|Delaware}}
{{PresRow|1980|Republican|76,898|76,897|14,632|Delaware}}
{{PresRow|1976|Democratic|80,074|87,521|2,743|Delaware}}
{{PresRow|1972|Republican|100,681|70,190|2,085|Delaware}}
{{PresRow|1968|Republican|70,014|68,468|17,931|Delaware}}
{{PresRow|1964|Democratic|54,767|91,752|374|Delaware}}
{{PresRow|1960|Democratic|69,284|73,364|326|Delaware}}
{{PresRow|1956|Republican|71,133|56,405|275|Delaware}}
{{PresRow|1952|Republican|62,658|58,387|351|Delaware}}
{{PresRow|1948|Democratic|47,451|48,117|1,433|Delaware}}
{{PresRow|1944|Democratic|37,783|49,588|318|Delaware}}
{{PresRow|1940|Democratic|41,508|52,167|0|Delaware}}
{{PresRow|1936|Democratic|37,851|47,315|600|Delaware}}
{{PresRow|1932|Republican|39,844|32,872|1,393|Delaware}}
{{PresRow|1928|Republican|47,641|22,464|307|Delaware}}
{{PresRow|1924|Republican|35,427|17,842|4,582|Delaware}}
{{PresRow|1920|Republican|36,600|24,252|1,939|Delaware}}
{{PresRow|1916|Republican|16,666|14,894|916|Delaware}}
{{PresRow|1912|Democratic|8,340|13,009|8,035|Delaware}}
{{PresRow|1908|Republican|14,987|12,965|701|Delaware}}
{{PresRow|1904|Republican|13,198|11,170|536|Delaware}}
{{PresRow|1900|Republican|13,646|10,644|350|Delaware}}
{{PresRow|1896|Republican|12,344|9,632|1,011|Delaware}}
{{PresRow|1892|Democratic|10,383|10,583|358|Delaware}}
{{PresRow|1888|Democratic|6,130|8,463|192|Delaware}}
{{PresRow|1884|Democratic|7,809|8,554|64|Delaware}}
{{PresRow|1880|Republican|7,724|7,623|43|Delaware}}
{{PresRow|1876|Democratic|6,054|6,613|0|Delaware}}
{{PresRow|1872|Republican|5,844|4,564|149|Delaware}}
{{PresRow|1868|Democratic|4,208|4,943|0|Delaware}}
{{PresRow|1864|Republican|4,274|3,813|0|Delaware}}
{{PresRow|1860|Southern Democratic|2,073|719|3,004|Delaware}}
{{PresRow|1856|Democratic|306|3,577|2,737|Delaware}}
{{PresRow|1852|Democratic|2,768|3,038|62|Delaware}}
{{PresRow|1848|Whig|3,091|2,717|80|Delaware}}
{{PresRow|1844|Whig|2,819|2,678|6|Delaware}}
{{PresRow|1840|Whig|2,321|2,195|10|Delaware}}
{{PresRow|1836|Democratic|1,673|1,814|5|Delaware}}
{{PresRow|1832|Democratic|1,335|1,715|0|Delaware}}
|}
{{U.S. SenHead|place=New Castle County, Delaware|Seat=1|source=<ref>{{cite web|url=https://uselectionatlas.org/RESULTS/state.php?fips=36&f=0&off=99|title=Dave Leip's Atlas of U.S. Presidential Elections – Sate Data|first=David|last=Leip|website=uselectionatlas.org}}</ref>}}
<!-- U.S. SenRow should be {{U.S. SenRow|Year|Winning party|GOP vote #|Dem vote #|3rd party vote #|State}} -->
{{U.S. SenRow|2024|Democratic|82,475|176,195|11,335|Delaware}}
{{U.S. SenRow|2018|Democratic|59,526|145,428|5,369|Delaware}}
{{U.S. SenRow|2012|Democratic|56,666|177,244|8,926|Delaware}}
{{U.S. SenFoot}}
{{U.S. SenHead|place=New Castle County, Delaware|Seat=2|source=<ref>{{cite web|url=https://uselectionatlas.org/RESULTS/state.php?fips=36&f=0&off=99|title=Dave Leip's Atlas of U.S. Presidential Elections – Sate Data|first=David|last=Leip|website=uselectionatlas.org}}</ref>}}
<!-- U.S. SenRow should be {{U.S. SenRow|Year|Winning party|GOP vote #|Dem vote #|3rd party vote #|State}} -->
{{U.S. SenRow|2020|Democratic|80,081|191,774|7,607|Delaware}}
{{U.S. SenRow|2014|Democratic|45,229|84,985|2,948|Delaware}}
{{U.S. SenRow|2010|Democratic|57,649|123,678|1,271|Delaware}}
{{U.S. SenFoot}}

===State government===
{{Hidden begin
|titlestyle = background:#ccccff;
|title      = Gubernatorial elections results
}}
{| class="wikitable" style="float:right; font-size:95%;"
|+ Gubernatorial elections results<ref>{{cite web|url=https://uselectionatlas.org/RESULTS/state.php?fips=36&f=0&off=99|title=Dave Leip's Atlas of U.S. Presidential Elections – Sate Data|first=David|last=Leip|website=uselectionatlas.org}}</ref>
|- bgcolor=lightgrey
! Year
! [[Republican Party (United States)|Republican]]
! [[Democratic Party (United States)|Democratic]]
! [[Third Party (United States)|Third parties]]
|-
|  style="text-align:center;" {{Party shading/Democratic}}|'''[[2024 Delaware gubernatorial election|2024]]'''
|  style="text-align:center;" {{Party shading/Republican}}|35.7% ''95,746''
|  style="text-align:center;" {{Party shading/Democratic}}|'''64.3%''' ''172,412''
|  style="text-align:center; background:honeyDew;"|0.0% ''0''
|-
|  style="text-align:center;" {{Party shading/Democratic}}|'''[[2020 Delaware gubernatorial election|2020]]'''
|  style="text-align:center;" {{Party shading/Republican}}|29.48% ''82,545''
|  style="text-align:center;" {{Party shading/Democratic}}|'''68.45%''' ''191,678''
|  style="text-align:center; background:honeyDew;"|2.07% ''5,816''
|-
|  style="text-align:center;" {{Party shading/Democratic}}|'''[[2016 Delaware gubernatorial election|2016]]'''
|  style="text-align:center;" {{Party shading/Republican}}|31.05% ''77,839''
|  style="text-align:center;" {{Party shading/Democratic}}|'''66.21%''' ''165,973''
|  style="text-align:center; background:honeyDew;"|2.75% ''6,879''
|-
|  style="text-align:center;" {{Party shading/Democratic}}|'''[[2012 Delaware gubernatorial election|2012]]'''
|  style="text-align:center;" {{Party shading/Republican}}|22.1% ''53,510''
|  style="text-align:center;" {{Party shading/Democratic}}|'''75.93%''' ''183,858''
|  style="text-align:center; background:honeyDew;"|1.97% ''4,871''
|}
{{Hidden end}}

The [[Delaware Department of Services for Children, Youth, and Their Families]] (DSCYF) has its headquarters in the Delaware Youth and Family Center (DYFC), located in [[unincorporated area|unincorporated]] New Castle County, near [[Wilmington, Delaware|Wilmington]].<ref>"[https://kids.delaware.gov/contact/ Contact Information]." [[Delaware Department of Services for Children, Youth, and Their Families]]. Retrieved August 30, 2010.</ref><ref>"[https://kids.delaware.gov/locations/ Office locations]." [[Delaware Department of Services for Children, Youth, and Their Families]]. Retrieved August 30, 2010.</ref> Several DSCYF juvenile facilities, including the New Castle County Detention Center (NCCDC),<ref>"[http://kids.delaware.gov/yrs/yrs_nccdc/yrs_nccdc.shtml New Castle County Detention Center] {{webarchive|url=https://web.archive.org/web/20100810003529/http://kids.delaware.gov/yrs/yrs_nccdc/yrs_nccdc.shtml |date=August 10, 2010 }}." [[Delaware Department of Services for Children, Youth, and Their Families]]. Retrieved August 30, 2010.</ref> the Ferris School for Boys,<ref>"[http://kids.delaware.gov/yrs/yrs_ferris/yrs_ferris.shtml Ferris School for Boys] {{webarchive|url=https://web.archive.org/web/20100810003527/http://kids.delaware.gov/yrs/yrs_ferris/yrs_ferris.shtml |date=August 10, 2010 }}." Delaware Department of Services for Children, Youth, and Their Families. Retrieved August 30, 2010.</ref> and the Grace and Snowden Cottages are in unincorporated New Castle County.<ref>"[http://kids.delaware.gov/yrs/yrs_gracesnowden/yrs_GraceWebPage.shtml Grace/Snowden Cottages] {{Webarchive|url=https://web.archive.org/web/20100810003524/http://kids.delaware.gov/yrs/yrs_gracesnowden/yrs_GraceWebPage.shtml |date=August 10, 2010 }}." [[Delaware Department of Services for Children, Youth, and Their Families]]. Retrieved August 30, 2010.</ref>

Several [[Delaware Department of Correction]] facilities are located in the county. The [[James T. Vaughn Correctional Center]] (JTVCC), formerly the Delaware Correctional Center, is a men's prison in unincorporated New Castle County, housing sentenced prisoners; Vaughn opened in 1971.<ref>"[https://web.archive.org/web/20070701223018/http://doc.delaware.gov/BOP/PrisonDCC.shtml James T. Vaughn Correctional Center] ." [[Delaware Department of Correction]]. Retrieved August 30, 2010.</ref> The [[Howard R. Young Correctional Institution]], renamed from Multi-Purpose Criminal Justice Facility in 2004 and housing both pretrial and posttrial male prisoners, is located in [[Wilmington, Delaware|Wilmington]]; it opened in 1982.<ref>"[https://archive.today/20120708013016/http://doc.delaware.gov/BOP/PrisonMPCJF.shtml Howard R. Young Correctional Institution] ." [[Delaware Department of Correction]]. Retrieved August 30, 2010.</ref> The [[Delores J. Baylor Correctional Institution]], a women's prison housing pretrial and posttrial prisoners, is located in unincorporated New Castle County.<ref name="Baylorprofile">"[https://web.archive.org/web/20070429060106/http://doc.delaware.gov/BOP/PrisonBWCI.shtml Delores J. Baylor Correctional Institution] ." [[Delaware Department of Correction]]. Retrieved August 30, 2010.</ref><ref>"[http://doc.delaware.gov/Directions%20to%20new%20entrance%20for%20Baylor.pdf Directions to the new entrance for the DELORES J. BAYLOR WOMEN'S CORRECTIONAL INSTITUTION] {{Webarchive|url=https://web.archive.org/web/20101103070934/http://www.doc.delaware.gov/Directions%20to%20new%20entrance%20for%20Baylor.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.doc.delaware.gov/Directions%20to%20new%20entrance%20for%20Baylor.pdf |archive-date=2022-10-09 |url-status=live |date=November 3, 2010 }}." [[Delaware Department of Correction]]. Retrieved August 30, 2010.</ref> Baylor opened on December 29, 1991.<ref name="Baylorprofile"/> The Delaware male death row was in the JTVCC, while the female death row was in Baylor.<ref name="DelawareDR">"[http://www.doc.delaware.gov/information/deathrow_factsheet.shtml Death Row Fact Sheet] {{webarchive|url=https://web.archive.org/web/20100818231840/http://doc.delaware.gov/information/deathrow_factsheet.shtml |date=August 18, 2010 }}." [[Delaware Department of Correction]]. Retrieved August 16, 2010.</ref> Executions were to occur at JTVCC,<ref>"[https://www.doc.delaware.gov/BOP/PrisonDCC.shtml JAMES T VAUGHN CORRECTIONAL CENTER (formerly DELAWARE CORRECTIONAL CENTER)]." [[Delaware Department of Correction]]. Retrieved August 16, 2010.</ref> prior to the 2016 suspension of it by the [[Delaware Supreme Court]].<ref>{{cite web|last=Petrowich|first=Sarah|url=https://www.delawarepublic.org/politics-government/2024-06-27/legislators-approve-removing-the-death-penalty-from-delaware-law|title=Legislators approve removing the death penalty from Delaware law|publisher=[[Delaware Public Radio]]|date=2024-06-29|access-date=2024-06-29}}</ref>

New Castle elects a substantial majority of the state legislature, with 27 state house districts and 17 state senate districts based in the county.

==Communities==
{{Main articles|List of municipalities in Delaware|List of places in Delaware}}
New Castle County is home to two minor league sports teams: the [[Wilmington Blue Rocks]] (baseball) and the [[Delaware Blue Coats]] (basketball), both of which play in Wilmington. It also has a professional auto racing track in New Castle known as Airport Speedway, with races on Saturday nights throughout the summer.
[[File:Wilmington Delaware skyline.jpg|thumb|right|Wilmington]]
[[File:Newark DE Main Street.jpg|thumb|right|Newark]]
[[File:Middletown DE.jpg|thumb|right|Middletown]]

===Cities===
* [[Delaware City, Delaware|Delaware City]]
* [[New Castle, Delaware|New Castle]]
* [[Newark, Delaware|Newark]]
* [[Wilmington, Delaware|Wilmington]]

===Towns===
{{div col}}
* [[Bellefonte, Delaware|Bellefonte]]
* [[Clayton, Delaware|Clayton]] (partly in [[Kent County, Delaware|Kent County]])
* [[Elsmere, Delaware|Elsmere]]
* [[Middletown, Delaware|Middletown]]
* [[Newport, Delaware|Newport]]
* [[Odessa, Delaware|Odessa]]
* [[Smyrna, Delaware|Smyrna]] (partly in [[Kent County, Delaware|Kent County]])
* [[Townsend, Delaware|Townsend]]
{{div col end}}

===Villages===
* [[Arden, Delaware|Arden]]
* [[Ardencroft, Delaware|Ardencroft]]
* [[Ardentown, Delaware|Ardentown]]

===Census-designated places===
{{div col}}
* [[Bear, Delaware|Bear]]
* [[Brookside, Delaware|Brookside]]
* [[Claymont, Delaware|Claymont]]
* [[Edgemoor, Delaware|Edgemoor]]
* [[Glasgow, Delaware|Glasgow]]
* [[Greenville, Delaware|Greenville]]
* [[Hockessin, Delaware|Hockessin]]
* [[North Star, Delaware|North Star]]
* [[Pike Creek, Delaware|Pike Creek]]
* [[Pike Creek Valley, Delaware|Pike Creek Valley]]
* [[Saint Georges, Delaware|St. Georges]]
* [[Wilmington Manor, Delaware|Wilmington Manor]]
{{div col end}}

===Unincorporated communities===
{{div col}}
* [[Appoquinimink Hundred]]
* [[Alapocas, Delaware|Alapocas]]
* [[Centerville, Delaware|Centerville]]
* [[Christiana, Delaware|Christiana]]
* [[Collins Park, Delaware|Collins Park]]
* [[Granogue, Delaware|Granogue]]
* [[Holly Oak, Delaware|Holly Oak]]
* [[Marshallton, Delaware|Marshallton]]
* [[Mill Creek, Delaware|Mill Creek]]
* [[Minquadale, Delaware|Minquadale]]
* [[Montchanin, Delaware|Montchanin]]
* [[Mount Pleasant, Delaware|Mount Pleasant]]
* [[Ogletown, Delaware|Ogletown]]
* [[Port Penn, Delaware|Port Penn]]
* [[Rockland, Delaware|Rockland]]
* [[Stanton, Delaware|Stanton]]
* [[Talleyville, Delaware|Talleyville]]
* [[Wooddale, Delaware|Wooddale]]
{{div col end}}

=== Ghost towns ===
{{Main articles|List of ghost towns in Delaware}}
{{div col}}
* [[Glenville, Delaware|Glenville]]
* [[Zwaanendael Colony|Zwaanendael(also known as Swaanendael, Zwaanendael Colony, Swaanendael Colony]]

{{div col end}}

==Education==
===K-12 education===
; School districts<ref>{{cite web|url=https://www2.census.gov/geo/maps/DC2020/PL20/st10_de/schooldistrict_maps/c10003_new_castle/DC20SD_C10003.pdf |archive-url=https://ghostarchive.org/archive/20221009/https://www2.census.gov/geo/maps/DC2020/PL20/st10_de/schooldistrict_maps/c10003_new_castle/DC20SD_C10003.pdf |archive-date=October 9, 2022 |url-status=live|title=2020 CENSUS - SCHOOL DISTRICT REFERENCE MAP: New Castle County, DE|publisher=[[U.S. Census Bureau]]|access-date=July 19, 2022}} - [https://www2.census.gov/geo/maps/DC2020/PL20/st10_de/schooldistrict_maps/c10003_new_castle/DC20SD_C10003_SD2MS.txt Text list] - This listing only includes geographical school districts and not county-wide overlay districts.</ref>
{{div col|colwidth=30em}}
* [[Appoquinimink School District]]
* [[Brandywine School District]]
* [[Christina School District]]
* [[Colonial School District (Delaware)|Colonial School District]]
* [[Red Clay Consolidated School District]]
* [[Smyrna School District]]
{{div col end}}
County-wide overlay district: [[New Castle County Vocational-Technical School District]]

In the period of de jure [[educational segregation in the United States]], K-12 students of black African descent attended [[History of African-American education|segregated schools]]. Middletown School District 120 operated [[Louis L. Redding Comprehensive High School for New Castle County]] to house high school students of black African descent during the period 1953 to 1966. Desegregation occurred after 1966.<ref>{{cite web|last=Mowery|first=Roger|url=https://archivesfiles.delaware.gov/ebooks/Delaware_School_Districts_1974.pdf|title=Delaware School District Organization and Boundaries|publisher=[[Delaware State Department of Instruction]]|place=[[Dover, Delaware]]|year=1974|page=6 (PDF p. 12/97)|access-date=2025-03-30}}</ref> Redding was the black school for the Middletown area.<ref>{{cite web|url=https://archives.delaware.gov/delaware-historical-markers/louis-l-redding-comprehensive-high-school/|title=Louis L. Redding Comprehensive High School|publisher=State of Delaware|access-date=2025-04-01}}</ref> Wilmington's segregated black high school was [[Howard High School (Delaware)|Howard High School]].<ref name=BarrishEichmann>{{cite web|last1=Barrish|first1=Cris|last2=Eichmann|first2=Mark|url=https://whyy.org:443/episodes/could-bringing-back-wilmington-high-help-fix-school-inequities/|title=Could bringing back Wilmington High help fix school inequities?|publisher=[[WHYY-TV|WHYY]]|date=2020-01-18|accessdate=2021-07-03}}</ref>

In 1978 the [[Alexis I. DuPont School District]], [[Alfred I. DuPont School District]], [[Claymont School District]], [[Conrad School District]], [[De Le Warr School District]], [[Marshallton-McKean School District]], [[Mount Pleasant School District (Delaware)|Mount Pleasant School District]], [[New Castle-Gunning Bedford School District]], [[Newark School District (Delaware)|Newark School District]], [[Stanton School District]], and [[Wilmington School District]] all merged to form the [[New Castle County School District]]. In 1981 that district was divided into the Christina, Colonial, Red Clay, and Brandywine districts.<ref name=Delgovhist>{{cite web|url=https://archives.delaware.gov/delaware-agency-histories/new-castle-county-school-district/|title=New Castle County School District|publisher=Government of Delaware|access-date=2025-04-01}}</ref>

; State-owned schools
* [[Delaware School for the Deaf]]

; Charter schools
{{div col|colwidth=30em}}
*[[Charter School of Wilmington]]
*[[Delaware Military Academy]]
*[[MOT Charter School]]
*[[Newark Charter School]]
{{div col end}}

Closed:
*[[Pencader Charter High School|Pencader Charter HS]]

; Private schools
In 2010, 18.8% of the county students enrolled in K-12 schools were in private institutions.<ref>{{cite web|url=https://www.delawarepublic.org/2010-12-16/private-schools-increasing-financial-aid-to-retain-students|title=Private schools increasing financial aid to retain students |publisher=[[Delaware Public Media]]|date=2010-12-16|access-date=2025-03-30|quote=In Delaware, with the nation’s highest percentage of private school enrollment,[...]}}</ref>
{{div col|colwidth=30em}}
* [[Archmere Academy]]
* [[Delaware Valley Classical School]]
* [[Centreville Layton School]]
* [[Padua Academy]]
* [[Red Lion Christian Academy]]
* [[St. Andrew's School (Delaware)|St. Andrew's School]]
* [[St. Anne's Episcopal School]]
* [[St. Elizabeth High School (Delaware)|St. Elizabeth High School]]
* [[St. Mark's High School]]
* [[Salesianum School]]
* [[Sanford School]]
* [[Tatnall School]]
* [[Tower Hill School]]
* [[Ursuline Academy (Delaware)|Ursuline Academy]]
* [[Wilmington Christian School]]
* [[Wilmington Friends School]]
* [[Wilmington Montessori School]]
{{div col end}}

Closed private schools:
* [[St. Mary's School (Wilmington, Delaware)|St. Mary's]]

===Tertiary===
{{div col|colwidth=30em}}
* [[Delaware State University]] – Wilmington Campus
* [[Delaware Technical & Community College]] – Wilmington Campus
* [[Goldey-Beacom College]]
* [[University of Delaware]] – Main Campus, Wilmington Campus and Downtown Building
* [[Wilmington University]] – Wilmington Campus
* [[Widener University Delaware Law School]]
{{div col end}}

Closed:
* [[Delaware College of Art & Design]]

===Libraries===
New Castle County Library has the following branches:<ref>{{cite web|url=https://www.newcastlede.gov/287/Branches|title=Branches|publisher=New Castle County Library|access-date=2025-03-30}}</ref>
{{div col|colwidth=30em}}
* Appoquinimink Community Library
* [[Bear, Delaware|Bear]] Library
* [[Brandywine Hundred]] Library
* [[Claymont, Delaware|Claymont]] Library
* [[Elsmere, Delaware|Elsmere]] Library
* [[Hockessin, Delaware|Hockessin]] Library
* Kirkwood Library
* [[Newark, Delaware|Newark]] Library
* Route 9 Library & Innovation Center
* Woodlawn Library
{{div col end}}

The Wilmington Library has two locations: Wilmington Branch and North Wilmington Branch.<ref>{{cite web|url=https://wilmington.lib.de.us/north-branch/|title=North Wilmington Branch|publisher=Wilmington Library|access-date=2025-03-30}}</ref>

Other municipal libraries include:
* Corbit-Calloway Memorial Library in [[Odessa, Delaware|Odessa]]<ref>{{cite web|url=https://corbitcalloway.lib.de.us/|title=Home|publisher=Corbit-Calloway Memorial Library|access-date=2025-03-30}}</ref>
* [[Delaware City, Delaware|Delaware City]] Library<ref>{{cite web|url=https://delawarecity.lib.de.us/|title=Home|publisher=Delaware City Library|access-date=2025-03-30}}</ref>
* [[New Castle, Delaware|New Castle]] Library<ref>{{cite web|url=https://newcastlelibrary.lib.de.us/|title=Home|publisher=New Castle Library|access-date=2025-03-30}}</ref>

Former county libraries:
* Concord Pike<ref>{{cite web|url=http://www.lib.de.us/libraries/de-libs/tipcat.shtml|archive-url=https://web.archive.org/web/20000816021259/http://www.lib.de.us/libraries/de-libs/tipcat.shtml|title=TIPCAT|publisher=Delaware Libraries|archive-date=2000-08-16|access-date=2025-03-30}}</ref> - Began operations in 1959, and replaced in 2003 by the Brandywine Hundred Library.<ref>{{cite web|url=https://www.newcastlede.gov/294/Brandywine-Hundred-Library|title=Brandywine Hundred Library|publisher=New Castle County|access-date=2025-03-30}}</ref>

==See also==
{{Portal|Philadelphia|Delaware}}
* [[National Register of Historic Places listings in New Castle County, Delaware]]
* [[Morris Branch (Corks Point Ditch tributary)]]
* [[Hindu Temple of Delaware]]

==References==
{{reflist|30em}}

==External links==
{{commons category}}
* {{official website|http://www.nccde.org}}
* [https://web.archive.org/web/20031126144007/http://datamil.udel.edu/ Delaware Map Data]

{{Geographic location
|Centre    = New Castle County, Delaware
|North     =
|Northeast = [[Delaware County, Pennsylvania]] and [[Gloucester County, New Jersey]]
|East      = [[Salem County, New Jersey]]
|Southeast =
|South     = [[Kent County, Delaware|Kent County]]
|Southwest = [[Kent County, Maryland]]
|West      = [[Cecil County, Maryland]]
|Northwest = [[Chester County, Pennsylvania]]
}}
{{New Castle County, Delaware}}
{{Delaware}}
{{Delaware Valley}}
{{Authority control}}
{{Coord|39.58|-75.64|display=title|type:adm2nd_region:US-DE_source:UScensus1990}}

[[Category:New Castle County, Delaware| ]]
[[Category:Delaware counties]]
[[Category:1637 establishments in North America]]
[[Category:Populated places established in 1637]]
[[Category:17th-century establishments in New Sweden]]
[[Category:1637 establishments in the Swedish colonial empire]]