Interstate 380 (I-380) is a short east–west

auxiliary Interstate Highway Auxiliary Interstate Highways (also called three-digit Interstate Highways) are a supplemental subset of the freeways within the Interstate Highway System of the United States. Auxiliary routes are generally classified as spur routes, which conn ...

in the

San Francisco Bay Area The San Francisco Bay Area, often referred to as simply the Bay Area, is a populous region surrounding the San Francisco, San Pablo, and Suisun Bay estuaries in Northern California. The Bay Area is defined by the Association of Bay Area Go ...

of Northern California, connecting

I-280 Interstate 280 may refer to multiple highways, all of which are or were related to Interstate 80: * Interstate 280 (California), a north–south freeway running from San Jose to San Francisco * Interstate 280 (Iowa–Illinois), part of the beltway ...

San Bruno San Bruno (Spanish for " St. Bruno") is a city in San Mateo County, California, United States, incorporated in 1914. The population was 43,908 at the 2020 United States Census. The city is between South San Francisco and Millbrae, adjacent to ...

to US Route 101 (US 101) near San Francisco International Airport. The highway primarily consists of only three intersections: I-280, State Route 82 (SR 82/ El Camino Real), and US 101. Like the nearby I-280, I-380 never connects to

I-80 Interstate 80 (I-80) is an east–west transcontinental freeway that crosses the United States from downtown San Francisco, California, to Teaneck, New Jersey, in the New York metropolitan area. The highway was designated in 1956 as one o ...

, its parent Interstate Highway. However, there is no rule that says that spur routes need to. (Similarly, the spur route I-795 branches off from I-695, a beltway around

Baltimore Baltimore ( , locally: or ) is the List of municipalities in Maryland, most populous city in the U.S. state of Maryland, fourth most populous city in the Mid-Atlantic (United States), Mid-Atlantic, and List of United States cities by popula ...

, and is only indirectly linked to

I-95 Interstate 95 (I-95) is the main north–south Interstate Highway on the East Coast of the United States, running from US Route 1 (US 1) in Miami, Florida, to the Houlton–Woodstock Border Crossing between Maine and the Canadia ...

.) I-380 is officially known as the Quentin L. Kopp Freeway, named after the prominent California state senator from

San Mateo County San Mateo County ( ), officially the County of San Mateo, is a county located in the U.S. state of California. As of the 2020 census, the population was 764,442. Redwood City is the county seat, and the third most populated city following Daly ...

. This highway was previously named the Portola Freeway to honor the 18th-century Spanish explorer

Gaspar de Portolá Gaspar de Portolá y Rovira (January 1, 1716 – October 10, 1786) was a Spanish military officer, best known for leading the Portolá expedition into California and for serving as the first Governor of the Californias. His expedition laid the ...

, whose expedition in 1769–1770 discovered the San Francisco Bay, from a viewpoint on the Sweeney Ridge located between San Bruno and Pacifica.

Route description

I-380 begins at a junction with I-280 in San Bruno. This junction was only partially built, with room to accommodate a proposed freeway extension west toward SR 1. The freeway itself lacks overhead guide signs mentioning I-380. It then travels east through the city of San Bruno, intersecting with SR 82 ( El Camino Real) before reaching US 101. At its terminus at US 101, the mainline lanes of I-380 continue to North Access Road. The ramps to and from southbound US 101 provide connections to collector–distributor roads leading directly to San Francisco International Airport, allowing traffic between the Interstate and the airport to avoid merging with the main traffic lanes of US 101. I-380 is part of the

California Freeway and Expressway System The California Freeway and Expressway System is a system of existing or planned freeways and expressways in the U.S. state of California. It encompasses both State highways and federal highways in California. It is defined by Article 2 (comme ...

and is part of the National Highway System, a network of highways that are considered essential to the country's economy, defense, and mobility by the

Federal Highway Administration The Federal Highway Administration (FHWA) is a division of the United States Department of Transportation that specializes in highway transportation. The agency's major activities are grouped into two programs, the Federal-aid Highway Program ...

(FHWA).

History

There were plans to extend I-380 west to SR 1 (Cabrillo Highway), but, due to the route's passing over the

San Andreas Fault The San Andreas Fault is a continental transform fault that extends roughly through California. It forms the tectonic boundary between the Pacific Plate and the North American Plate, and its motion is right-lateral strike-slip (horizonta ...

and opposition from members of the local community, this project was abandoned. The westbound lanes of I-380 branch off to the right at I-280, leaving a wide, paved space which would carry the freeway extension under I-280 toward SR 1. This space is currently often used as storage space for equipment used in highway maintenance. A pair of unused bridges crossing over the I-280 south to I-380 east offramp remain as evidence. Chapter 2, Article 3, Section 608 of the California Streets and Highways Code legally defines Route 380 as traveling from "Route 1 near Pacifica to Route 280 in San Bruno", and the exit numbers assigned at I-280 start at 5 instead of 1 or 0.

Exit list

Under the official exit list by Caltrans, mileage is measured from the unconstructed western terminus at SR 1 near Pacifica. It starts at the location of the SR 82 interchange, labeling the start of the I-280 ramps at that same point.

References

External links

Interstate 380 @ California HighwaysCaltrans: Route 380 highway conditionsMap of 1974 plan to extend the freeway to the west
{{3di, 80 3 California 80-3 380 80-3 California Interstate 80-3

Route description

History

Exit list

See also

References

External links