# Interstate 505

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Interstate Highway in California

For the never-built spur in Portland, Oregon, see [Interstate 505 (Oregon)](/source/Interstate_505_(Oregon)).

"I-505" redirects here. For the submarine, see [Japanese submarine I-505](/source/Japanese_submarine_I-505).

Interstate 505 I-505 highlighted in red Route information Auxiliary route of I-5 Maintained by Caltrans Length 32.99 mi[1] (53.09 km) Existed 1977–present NHS Entire route Major junctions South end I-80 in Vacaville Major intersections SR 128 near Winters SR 16 near Madison North end I-5 near Dunnigan Location Country United States State California Counties Solano, Yolo Highway system Interstate Highway System Main Auxiliary Suffixed Business Future State highways in California Interstate US State Scenic History Pre‑1964 Unconstructed Deleted Freeways ← SR 480 → I-580

**Interstate 505** (**I-505**) is a north–south [auxiliary Interstate Highway](/source/List_of_auxiliary_Interstate_Highways) in the [Sacramento Valley](/source/Sacramento_Valley) in [Northern California](/source/Northern_California). It is a [spur](/source/Spur_route) auxiliary route of [I-5](/source/Interstate_5_in_California) that runs from near [Dunnigan](/source/Dunnigan%2C_California) south to [I-80](/source/Interstate_80_in_California) in [Vacaville](/source/Vacaville%2C_California). I-505 is primarily a rural Interstate, but travels through Vacaville and the city of [Winters](/source/Winters%2C_California). The highway is the primary route connecting the [San Francisco Bay Area](/source/San_Francisco_Bay_Area) and the northern [Sacramento Valley](/source/Sacramento_Valley), bypassing [Sacramento](/source/Sacramento%2C_California) 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](/source/Shasta_Cascade) and the [Pacific Northwest](/source/Pacific_Northwest).

## Route description

The entirety of I-505 is defined in section 617 of the [California Streets and Highways Code](/source/California_Codes) as **Route 505**, and that the highway is from "[Route 80](/source/Interstate_80_in_California) near [Vacaville](/source/Vacaville%2C_California) to [Route 5](/source/Interstate_5_in_California) near [Dunnigan](/source/Dunnigan%2C_California)".[2] This definition roughly corresponds with the [Federal Highway Administration](/source/Federal_Highway_Administration) (FHWA)'s route logs of I-505.[3][4]

The southern terminus of I-505 is at I-80 next to the [Nut Tree Airport](/source/Nut_Tree_Airport) in the [Nut Tree](/source/Nut_Tree) area in [Vacaville](/source/Vacaville%2C_California). From there, it travels north about 10 miles (16 km) through rural areas near the western edge of the [Sacramento Valley](/source/Sacramento_Valley) before reaching [Winters](/source/Winters%2C_California). I-505 then skirts the eastern [city limits](/source/City_limits) of Winters, intersecting with [State Route 128](/source/California_State_Route_128)—the only exit in Winters. After leaving that city, the Interstate then proceeds north through rural areas again for about 20 miles (32 km), including an interchange with [California State Route 16](/source/California_State_Route_16) near [Madison](/source/Madison%2C_California), until it reaches its northern terminus with I-5 near [Dunnigan](/source/Dunnigan%2C_California).

For its entire length, I-505 is a four-lane freeway (two lanes in each direction) with a maximum speed limit of 70 mph (110 km/h), which is typical for rural Interstates in California.

I-505 is part of the [California Freeway and Expressway System](/source/California_Freeway_and_Expressway_System),[5] and is part of the [National Highway System](/source/National_Highway_System_(United_States)),[3] a network of highways that are considered essential to the country's economy, defense, and mobility by the [Federal Highway Administration](/source/Federal_Highway_Administration).[6]

## History

What is now I-505 was originally conceived as part of a loop Interstate with a directional suffix, I-5W.[7] However, I-5W and most of the other Interstates around the country with directional suffixes were eventually renumbered or eliminated, except [I-35E](/source/Interstate_35E_(disambiguation)) and [I-35W](/source/Interstate_35W_(disambiguation)) in Texas and Minnesota. [I-69](/source/Interstate_69) segments [I-69W](/source/I-69W), [I-69C](/source/I-69C), and [I-69E](/source/I-69E) in southern Texas have since been designated as well along with proposed suffixed segments for future extensions of [I-14](/source/Interstate_14#Proposed_extension) and [I-27](/source/Interstate_27#Numbering) to follow. The former route of I-5W now corresponds to [I-580](/source/Interstate_580_(California)) from I-5 south of [Tracy](/source/Tracy%2C_California) to [Oakland](/source/Oakland%2C_California), [I-80](/source/Interstate_80_in_California) 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.[8]

## Exit list

County Location mi [9] km Exit [9] Destinations Notes Solano Vacaville 0.00 0.00 1A I-80 west – San Francisco Southern terminus; I-80 exit 56 — Orange Drive / Nut Tree Road Northbound exit (only accessible from I-80 east) and entrance 1B I-80 east – Sacramento Southbound exit and northbound entrance; provides direct access to East Monte Vista Avenue; I-80 exit 56 1.45 2.33 1C Vaca Valley Parkway Signed as exit 1 northbound; serves Kaiser Permanente Vacaville Medical Center 3.06 4.92 3 Midway Road ​ 5.57 8.96 6 Allendale Road ​ 10.43 16.79 10 Putah Creek Road Yolo ​ 11.03 17.75 11 SR 128 west (Grant Avenue) / Russell Boulevard (CR E6 east) – Winters, Davis Eastern terminus of SR 128; western terminus of CR E6 ​ 14.66 23.59 15 Road 29A ​ 17.16 27.62 17 Road 27 ​ 21.25 34.20 21 SR 16 – Woodland, Esparto ​ 24.06 38.72 24 Road 19 ​ 28.08 45.19 28 Road 14 (CR E10) – Zamora ​ 30.74 49.47 31 Road 12A ​ 32.99 53.09 — I-5 north – Redding Northern terminus; no access to I-5 south; I-5 south exit 553 1.000 mi = 1.609 km; 1.000 km = 0.621 mi Incomplete access

## See also

- [California Roads portal](https://en.wikipedia.org/wiki/Portal:California_Roads)

## References

1. **[^](#cite_ref-bridgelog_1-0)** California Department of Transportation (October 2014). ["Log of Bridges on State Highways"](https://web.archive.org/web/20120701125434/http://www.dot.ca.gov/hq/structur/strmaint/brlog2.htm). Sacramento: California Department of Transportation.

1. **[^](#cite_ref-CSHC617_2-0)** ["Section 617"](https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=SHC&sectionNum=617.). *California Streets and Highways Code*. Sacramento: California Office of Legislative Counsel. Retrieved August 24, 2025.

1. ^ [***a***](#cite_ref-fhwa-nhs_3-0) [***b***](#cite_ref-fhwa-nhs_3-1) Federal Highway Administration (March 25, 2015). [*National Highway System: California (North)*](https://www.fhwa.dot.gov/planning/national_highway_system/nhs_maps/california/ca_californianorth.pdf) (PDF) (Map). Scale not given. Washington, DC: Federal Highway Administration. Retrieved July 29, 2017.

1. **[^](#cite_ref-FHWA_4-0)** ["Table 1: Auxiliary Routes of the Dwight D. Eisenhower National System Of Interstate and Defense Highways"](https://www.fhwa.dot.gov/planning/national_highway_system/interstate_highway_system/routefinder/table02.cfm). *FHWA Route Log and Finder List*. [Federal Highway Administration](/source/Federal_Highway_Administration). January 2025. Retrieved August 24, 2025.

1. **[^](#cite_ref-cafes_5-0)** ["Article 2 of Chapter 2 of Division 1"](https://leginfo.legislature.ca.gov/faces/codes_displayText.xhtml?lawCode=SHC&division=1.&title=&part=&chapter=2.&article=2.). *California Streets and Highways Code*. Sacramento: California Office of Legislative Counsel. Retrieved February 6, 2019.

1. **[^](#cite_ref-NHS-FHWA_6-0)** Natzke, Stefan; Neathery, Mike & Adderly, Kevin (June 20, 2012). ["What is the National Highway System?"](https://www.fhwa.dot.gov/planning/national_highway_system/). *National Highway System*. Washington, DC: Federal Highway Administration. Retrieved July 1, 2012.

1. **[^](#cite_ref-cahighways_5_7-0)** ["California Highways-Routes 1-8"](http://cahighways.org/001-008.html#005). *California Highways*. Retrieved September 3, 2012.

1. **[^](#cite_ref-8)** ["I-505 Stretch In Yolo To Open"](https://www.newspapers.com/clip/89608852/i-505-stretch-in-yolo-to-open/). *The Sacramento Bee*. August 11, 1977. p. B2. Retrieved November 26, 2021 – via [Newspapers.com](/source/Newspapers.com).

1. ^ [***a***](#cite_ref-calnexus_9-0) [***b***](#cite_ref-calnexus_9-1) [California Department of Transportation](/source/California_Department_of_Transportation), [California Numbered Exit Uniform System](/source/California_Numbered_Exit_Uniform_System), [Interstate 505 Freeway Interchanges](http://www.dot.ca.gov/trafficops/exit/docs/505.pdf), Retrieved on 2009-02-07.

## External links

**[KML file](https://en.wikipedia.org/w/index.php?title=Template:Attached_KML/Interstate_505&action=raw)** ([edit](https://en.wikipedia.org/w/index.php?title=Template:Attached_KML/Interstate_505&action=edit) · [help](https://en.wikipedia.org/wiki/Help:Attached_KML))

[Template:Attached KML/Interstate 505](https://en.wikipedia.org/wiki/Template:Attached_KML/Interstate_505)

KML is from Wikidata

Wikimedia Commons has media related to [Interstate 505 (California)](https://commons.wikimedia.org/wiki/Category:Interstate_505_(California)).

- [Caltrans: I-505 highway conditions](https://roads.dot.ca.gov/)

- [Caltrans Traffic Conditions Map](https://quickmap.dot.ca.gov/)

- [California Highway Patrol Traffic Incidents](https://cad.chp.ca.gov/)

- [California @ AARoads.com - I-505](http://www.aaroads.com/california/i-505_ca.html)

- [California Highways: I-505](http://www.cahighways.org/466-740.html#505)

v t e Auxiliary routes of Interstate 5 California 5E1 5W1 105 1051 205 3054 405 505 605 805 9052 Business Oregon 105 205 3053 405 5053 Washington 205 405 6053 705 Business 1Former 2Future 3Unbuilt 4Unsigned

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Adapted from the Wikipedia article [Interstate 505](https://en.wikipedia.org/wiki/Interstate_505) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Interstate_505?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.