View source for Interstate 505

{{short description|Interstate Highway in California}}
{{For|the never-built spur in Portland, Oregon|Interstate 505 (Oregon)}}
{{redirect|I-505|the submarine|Japanese submarine I-505}}
{{Use American English|date=April 2025}}
{{Use mdy dates|date=December 2022}}
{{Infobox road
|state=CA
|type=I
|route=505
|section=617
|map={{maplink-road|from=Interstate 505.map}}
|map_custom=yes
|map_notes=I-505 highlighted in red
|length_mi=32.99
|established=1977
|spur_of=5
|spur_type=I
|length_ref=<ref name=bridgelog>{{Caltrans bridgelog|date=October 2014}}</ref>
|direction_a=South
|terminus_a={{jct|state=CA|I|80}} in [[Vacaville, California|Vacaville]]
|junction={{plainlist
|*{{Jct|state=CA|SR|128}} near [[Winters, California|Winters]]
*{{Jct|state=CA|SR|16}} near [[Madison, California|Madison]]
}}
|direction_b=North
|terminus_b={{jct|state=CA|I|5}} near [[Dunnigan, California|Dunnigan]]
|counties=[[Solano County, California|Solano]], [[Yolo County, California|Yolo]]
|previous_type=CA
|previous_route=480
|next_type=I
|next_route=580
}}
'''Interstate&nbsp;505''' ('''I-505''') is a north–south [[List of auxiliary Interstate Highways|auxiliary Interstate Highway]] in the [[Sacramento Valley]] in [[Northern California]]. It is a [[Spur route|spur]] auxiliary route of [[Interstate 5 in California|I-5]] that runs from near [[Dunnigan, California|Dunnigan]] south to [[Interstate 80 in California|I-80]] in [[Vacaville, California|Vacaville]]. I-505 is primarily a rural Interstate, but travels through Vacaville and the city of [[Winters, California|Winters]]. The highway is the primary route connecting the [[San Francisco Bay Area]] and the northern [[Sacramento Valley]], bypassing [[Sacramento, California|Sacramento]] and its attendant city traffic. Thus, it is a major route for travelers heading directly from the San Francisco Bay Area to the [[Shasta Cascade]] and the [[Pacific Northwest]].

[[Electric power transmission|Power lines]] connecting [[Path 15]] to [[Path 66]] follow the highway for a while, until one heads [[Ordinal direction|northeast]] and the other [[Ordinal directions|northwest]].

==Route description==
The entirety of I-505 is defined in section 617 of the [[California Codes|California Streets and Highways Code]] as '''Route 505''', and that the highway is from "[[Interstate 80 in California|Route 80]] near [[Vacaville, California|Vacaville]] to [[Interstate 5 in California|Route 5]] near [[Dunnigan, California|Dunnigan]]".<ref name="CSHC617">{{Cite web|url=https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=SHC&sectionNum=617.|title=Section 617|work=California Streets and Highways Code|publisher=California Office of Legislative Counsel|location=Sacramento|access-date=August 24, 2025}}</ref> This definition roughly corresponds with the [[Federal Highway Administration]] (FHWA)'s route logs of I-505.<ref name=fhwa-nhs /><ref name="FHWA">{{cite web|title=Table 1: Auxiliary Routes of the Dwight D. Eisenhower National System Of Interstate and Defense Highways|url=https://www.fhwa.dot.gov/planning/national_highway_system/interstate_highway_system/routefinder/table02.cfm|work=FHWA Route Log and Finder List|publisher = [[Federal Highway Administration]]|date=January 2025|access-date=August 24, 2025}}</ref>

The southern terminus of I-505 is at I-80 next to the [[Nut Tree Airport]] in the [[Nut Tree]] area in [[Vacaville, California|Vacaville]]. From there, it travels north about {{Convert|10|mi|km}} through rural areas near the western edge of the [[Sacramento Valley]] before reaching [[Winters, California|Winters]]. I-505 then skirts the eastern [[city limits]] of Winters, intersecting with [[California State Route 128|State Route 128]]—the only exit in Winters. After leaving that city, the Interstate then proceeds north through rural areas again for about {{Convert|20|mi|km}}, including an interchange with [[California State Route 16]] near [[Madison, California|Madison]], until it reaches its northern terminus with I-5 near [[Dunnigan, California|Dunnigan]].

For its entire length, I-505 is a four-lane freeway (two lanes in each direction) with a maximum speed limit of {{convert|70|mi/h|km/h|abbr=on}}, which is typical for rural Interstates in California.

I-505 is part of the [[California Freeway and Expressway System]],<ref name="cafes">{{CAFESystem}}</ref> and is part of the [[National Highway System (United States)|National Highway System]],<ref name=fhwa-nhs>{{FHWA NHS map|region=californianorth|access-date=July 29, 2017}}</ref> a network of highways that are considered essential to the country's economy, defense, and mobility by the [[Federal Highway Administration]].<ref name=NHS-FHWA>{{FHWA NHS}}</ref>

==History==
What is now I-505 was originally conceived as part of a loop Interstate with a directional suffix, I-5W.<ref name="cahighways_5">{{cite web | url=http://cahighways.org/001-008.html#005 | title=California Highways-Routes 1-8 | work=California Highways | access-date=2012-09-03}}</ref> However, I-5W and most of the other Interstates around the country with directional suffixes were eventually renumbered or eliminated, except [[Interstate 35E (disambiguation)|I-35E]] and [[Interstate 35W (disambiguation)|I-35W]] in Texas and Minnesota. [[Interstate 69|I-69]] segments [[I-69W]], [[I-69C]], and [[I-69E]] in southern Texas have since been designated as well along with proposed suffixed segments for future extensions of [[Interstate 14#Proposed extension|I-14]] and [[Interstate 27#Numbering|I-27]] to follow. The former route of I-5W now corresponds to [[Interstate 580 (California)|I-580]] from I-5 south of [[Tracy, California|Tracy]] to [[Oakland, California|Oakland]], [[Interstate 80 in California|I-80]] from Oakland to Vacaville, and I-505 from Vacaville to I-5 near Dunnigan.

The northernmost section of I-505, between SR 16 in Madison and I-5 near Dunnigan, opened in August 1977.<ref>{{cite news |date=August 11, 1977 |title=I-505 Stretch In Yolo To Open |page=B2 |work=The Sacramento Bee |url=https://www.newspapers.com/clip/89608852/i-505-stretch-in-yolo-to-open/ |via=[[Newspapers.com]] |access-date=November 26, 2021}}</ref>
{{-}}

==Exit list==
{{CAinttop|exit|length_ref=<br><ref name="calnexus">[[California Department of Transportation]], [[California Numbered Exit Uniform System]], [http://www.dot.ca.gov/trafficops/exit/docs/505.pdf Interstate 505 Freeway Interchanges], Retrieved on 2009-02-07.</ref>|exit_ref=<br><ref name="calnexus" />
}}
{{CAint|exit
|county=Solano
|cspan=7
|location=Vacaville
|lspan=5
|mile=0.00
|mspan=3
|exit=1A
|road={{Jct|state=CA|I|80|city1=San Francisco|dir1=west}}
|notes=Southern terminus; I-80 exit 56
}}
{{CAint|exit
|type=incomplete
|mile=none
|exit=—
|road=Orange Drive / Nut Tree Road
|notes=Northbound exit (only accessible from I-80 east) and entrance
}}
{{CAint|exit
|mile=none
|exit=1B
|road={{Jct|state=CA|I|80|city1=Sacramento|dir1=east}}
|notes=Southbound exit and northbound entrance; provides direct access to East Monte Vista Avenue; I-80 exit 56
|type=incomplete
}}
{{CAint|exit
|mile=1.45
|exit=1C
|road=Vaca Valley Parkway
|notes=Signed as exit 1 northbound
}}
{{CAint|exit
|mile=3.06
|exit=3
|road=Midway Road
}}
{{CAint|exit
|location=none
|mile=5.57
|exit=6
|road=Allendale Road
}}
{{CAint|exit
|location=none
|mile=10.43
|exit=10
|road=Putah Creek Road
}}
{{CAint|exit
|county=Yolo
|cspan=8
|location=none
|mile=11.03
|exit=11
|road={{Jct|state=CA|SR|128|name1=Grant Avenue|road|Russell Boulevard ([[County Route E6 (California)|CR E6]] east)|dir1=west|city1=Winters|city2=Davis}}
|notes=Eastern terminus of SR&nbsp;128; western terminus of CR&nbsp;E6
}}
{{CAint|exit
|location=none
|mile=14.66
|exit=15
|road=Road&nbsp;29A
}}
{{CAint|exit
|location=none
|mile=17.16
|exit=17
|road=Road&nbsp;27
}}
{{CAint|exit
|location=none
|mile=21.25
|exit=21
|road={{Jct|state=CA|SR|16|city1=Woodland|city2=Esparto}}
}}
{{CAint|exit
|location=none
|mile=24.06
|exit=24
|road=Road&nbsp;19
}}
{{CAint|exit
|location=none
|mile=28.08
|exit=28
|road=Road&nbsp;14 ([[County Route E10 (California)|CR E10]])&nbsp;– [[Zamora, California|Zamora]]
}}
{{CAint|exit
|location=none
|mile=30.74
|exit=31
|road=Road&nbsp;12A
}}
{{CAint|exit
|type=incomplete
|location=none
|mile=32.99
|exit=—
|road={{Jct|state=CA|I|5|dir1=north|city1=Redding}}
|notes=Northern terminus; no access to I-5 south; I-5 south exit 553
}}
{{jctbtm|keys=incomplete|col=7}}

==See also==
*{{portal-inline|California Roads}}

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

==External links==
{{Attached KML|display=inline,title}}
{{commonscat}}
{{CASR external links|I|505}}
*[http://www.aaroads.com/california/i-505_ca.html California @ AARoads.com - I-505]
*[http://www.cahighways.org/466-740.html#505 California Highways: I-505]

{{I-5 aux}}

[[Category:Interstate Highways in California|05-5]]
[[Category:Auxiliary Interstate Highways|05-5]]
[[Category:Interstate 5|5]]
[[Category:San Francisco Bay Area freeways|505]]
[[Category:Roads in Solano County, California|Interstate 05-5]]
[[Category:Roads in Yolo County, California|Interstate 05-5]]