I-280 highlighted in red
|Defined by Streets and Highways Code § 580|
|Maintained by Caltrans|
|Length||57.510 mi (92.553 km)|
|Existed||September 15, 1955 by FHWA|
July 1, 1964 by Caltrans-present
|Junipero Serra Freeway between the San Mateo-Santa Clara county line and San Bruno|
|South end||/ in San Jose|
|North end||King Street, 5th Street in San Francisco|
|Counties||Santa Clara, San Mateo, San Francisco|
Interstate 280 (I-280) is a 57.5-mile-long (92.5 km) major north-south auxiliary Interstate Highway in the San Francisco Bay Area of Northern California. It runs from I-680 and US 101 in San Jose to King and Fifth Streets in San Francisco, running just to the west of the larger cities of San Francisco Peninsula for most of its route.
From I-880 in San Jose to State Route 1 in Daly City, I-280 was built and dedicated as the Junipero Serra Freeway, after the Spanish Franciscan friar who founded the first nine of 21 Spanish missions in California from San Diego to San Francisco. One of the dedication signs (in Daly City) still indicates that the Junipero Serra Freeway is known as the "World's Most Beautiful Freeway" due to its scenic route through the San Francisco Peninsula. From State Route 1 to the James Lick Freeway (U.S. 101) in San Francisco it is officially called the John F Foran Freeway (after a former member of the California State Legislature). From the James Lick Freeway to its northern end at King Street and Fifth Street, I-280 is called the Southern-Embarcadero Freeway.
I-280 is shown prominently on the app icon for Apple's iOS built-in Apple Maps app (and formerly the Google Maps app as well). This is because the highway goes through Cupertino, the home of Apple's headquarters.
The southern end of Interstate 280 is U.S. 101 in San Jose, where it acts as a continuation of Interstate 680 westward. In between San Jose and San Francisco, Interstate 280 passes through Santa Clara, Cupertino, Los Altos and Los Altos Hills before it settles along its scenic route just to the west of the cities of the San Francisco Peninsula in San Mateo County and just to the east of the Santa Cruz Mountains. I-280 re-emerges in a decidedly urbanized area in the city of San Bruno, passing through South San Francisco and Daly City before it runs across a southeastern swath of the city of San Francisco on the way to its northern terminus.
The segment of the Junipero Serra Freeway between Cupertino (SR 85) and Daly City (SR 1) has been called the "World's Most Beautiful Freeway" since its dedication in the 1960s. Drivers along this portion of Interstate 280 are treated to scenic views of the Santa Cruz Mountains to the west and, at a few points, San Francisco Bay to the east, and are isolated by hills from the cities to the east. Through much of this segment, the freeway is actually running just inside the eastern rim of the rift valley of the San Andreas Fault. A particularly attractive 6-mile (10 km) stretch of the freeway from Hillsborough to Belmont provides a view at Crystal Springs Reservoir, formed by water piped over 160 miles (260 km) from Hetch Hetchy Valley in Yosemite National Park, partly filling the rift valley.
For nearly all of its length, Interstate 280 runs roughly parallel and several miles to the west of US 101 (the Bayshore Freeway). Both freeways are north-south routes connecting San Jose with San Francisco; however, unlike I-280, the route that U.S. 101 takes between the two cities goes entirely through urbanized areas. The vast majority of the population of the San Francisco Peninsula lives somewhere between Interstate 280 and U.S. 101.
Interstate 280 does not currently intersect with Interstate 80, its 'parent' interstate, although it was originally intended to do so. The northern terminus of I-280 is now within about a mile of I-80's western terminus (at the interchange with US 101), but the two interstates do not directly connect; instead, I-280 complies with numbering conventions by virtue of its linkages to I-680 and I-880, both of which connect to I-80 at their northern termini. Although San Francisco planned and has had several opportunities to connect I-280 to I-80, it has chosen to use the money for other purposes. Instead, I-280's northernmost extension, which includes a significant double-deck section (with northbound traffic on the lower deck and southbound traffic on the upper), primarily functions now as a spur into Downtown San Francisco, as suggested by signage on northbound U.S. Route 101 at the Alemany Maze.
I-280 is part of the California Freeway and Expressway System, 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. I-280 is eligible for the State Scenic Highway System, and from the San Mateo-Santa Clara county line to the San Bruno city limits is officially designated as a scenic highway by the California Department of Transportation, meaning that it is a substantial section of highway passing through a "memorable landscape" with no "visual intrusions", where the potential designation has gained popular favor with the community. The Junipero Serra Freeway is the name of Interstate 280 from SR 1 in San Francisco to SR 17, as named by Assembly Concurrent Resolution 140, Chapter 208 in 1967, in honor of Spanish missionary Junípero Serra, who founded many of California's missions in the 18th century. I-280 from its southern terminus at U.S. 101 and Interstate 680 north to Interstate 880 in San Jose is part of the Sinclair Freeway (named after Joseph P. Sinclair, District Engineer for District 4 California Division of Highways). A 26-foot (8 m) high faux-sandstone statue of Father Serra kneeling and pointing over the freeway is located at a highway rest area just north of the Highway 92 intersection between the Bunker Hill Drive and Black Mountain Road exits on northbound I-280 in Hillsborough, and can be clearly seen by drivers in both directions.
Interstate 280 was added to the Interstate Highway System on September 15, 1955 as a route from San Jose north to San Francisco. This ran along the present alignment of I-280 south of San Francisco, but in San Francisco it ran north parallel to State Route 1, past the planned west end of Interstate 80 which would have been at the junction with the Panhandle Freeway just south of Fulton and Park Presidio, along what would have been the Park Presidio Freeway north to the south approach to the Golden Gate Bridge. At that point, I-280 would have met Interstate 480, which would have headed east on Doyle Drive (U.S. Route 101), the Golden Gate Freeway, and onto the Embarcadero Freeway to reach the San Francisco-Oakland Bay Bridge. I-480 would have continued south on the never-built section of the Southern-Embarcadero Freeway from Folsom and the Embarcadero to 5th and King Street, then along the present Southern-Embarcadero Freeway to meet the Southern Freeway (now I-280) near the Alemany Maze, which served as the 101A Bypass until I-280 was built. The I-280 number was approved on November 10, 1958.
In the 1964 renumbering, the Route 280 designation was officially applied to the planned route. This replaced SR 1 in San Francisco; the new SR 1 alignment turned northeast where I-280 now runs, quickly ending at State Route 82 (San Jose Avenue/Alemany Boulevard). SR 1, however, continued to be signed along its former (and current) alignment, which had not been upgraded to freeway standards.
A realignment approved January 1968 took I-280 onto its current route. This ran along what had been SR 1, SR 82, State Route 87 and I-480 (downgraded to a State Route then), ending at Interstate 80 at the west end of the Bay Bridge. This change was made on the state level in 1968, restoring SR 1 to its current alignment and truncating SR 82, SR 87 and SR 480.
For the scenic portion, the section of I-280 between SR 85 (Cupertino) and SR 84 (Woodside) was completed in the late 1960s. The section between SR 92 (San Mateo) and SR 84 was not completed until the 1970s. Until then, traffic was routed on Cañada Road between the two ends.
The short piece of I-280 between 3rd Street and SR 480 in downtown San Francisco was never built, and the piece from 5th Street south to U.S. Route 101 originally terminated mid-air, to connect to the second proposed location of a parallel bay bridge (which was never built) but was reconfigured to the King St on/off ramps after it was damaged by the 1989 earthquake. The piece between SR 480 and I-80 was torn down along with the rest of the Embarcadero Freeway; ramp stubs which would have connected the freeways were removed as part of the San Francisco-Oakland Bay Bridge Western Approach reconstruction project.
The interchange at the beginning of I-280 at I-680 and U.S. Route 101 in San Jose was constructed years before its completion. The three flyovers, with no connecting ramps, stood as a 110-foot-tall (33.5 m) monument to inefficiency for years in the 1970s, becoming the butt of local jokes. The highlight prank occurred in January 1976, when a 1960 Chevrolet Impala was placed on the highest bridge overnight, where it obviously would be impossible to drive. The following day, San Jose City Councilman Joe Colla was photographed standing next to the car, an image that was circulated across many newspapers. It has been suggested this stunt nudged the State of California to find the funds to complete the freeway. The ramps opened five years later in 1981. In 2010, a resolution was introduced in the state legislature to name it the Joe Colla Interchange in memory of the late councilman.
Except where prefixed with a letter, postmiles were measured on the road as it was in 1964, based on the alignment that existed at the time, and do not necessarily reflect current mileage. R reflects a realignment in the route since then, M indicates a second realignment, L refers an overlap due to a correction or change, and T indicates postmiles classified as temporary (for a full list of prefixes, see the list of postmile definitions). Segments that remain unconstructed or have been relinquished to local control may be omitted. The numbers reset at county lines; the start and end postmiles in each county are given in the county column.
|San Jose||R0.00||north (Sinclair Freeway) / (Bayshore Freeway) - Sacramento, San Francisco, Los Angeles||Southern terminus; US 101 north exit 384, south exit 385B; Sinclair Freeway continues east as I-680 north|
|R0.37||1A||McLaughlin Avenue||Southbound exit and northbound entrance|
|R1.29||1B||11th Street, 10th Street||Signed as exit 1 northbound|
|R1.99||2A||To / 7th Street, Virginia Street||Signed as exit 2 northbound|
|||2B||Almaden Boulevard, Vine Street||Southbound exit and northbound entrance|
|R2.52||3A||(Guadalupe Parkway)||SR 87 exit 5|
|R3.76||4||Race Street, Southwest Expressway||Northbound exit and southbound entrance|
|R3.99||Meridian Avenue||Southbound exit and northbound entrance|
|L4.66||5A||Leigh Avenue, Bascom Avenue|
|L5.41||5B||north / south - Oakland, Santa Cruz||West end of the Sinclair Freeway; SR 17 north exits 26A-B; I-880 south exit 1B|
|||5C||Stevens Creek Boulevard, West San Carlos Street||Northbound exit and southbound entrance|
|4.57||6||Winchester Boulevard||Southbound exit and northbound entrance|
|5.95||7||Saratoga Avenue - Saratoga|
|9||Lawrence Expressway (CR G2), Stevens Creek Boulevard|
|9.43||11||De Anza Boulevard||Former SR 85|
|10.74||12||- Mountain View, Santa Cruz, Gilroy||Signed as exits 12A (north) and 12B (south); SR 85 north exit 19, south exit 19A|
|Los Altos||11.45||13||Foothill Expressway (CR G5), Grant Road|
|Los Altos Hills||15.05||16||El Monte Road, Moody Road|
|||18.38||20||Page Mill Road (CR G3), Arastradero Road - Palo Alto|
|||20.61||22||Alpine Road - Portola Valley|
|||R1.61||24||Sand Hill Road - Menlo Park|
|R4.65||27||Farm Hill Boulevard|
|R6.60||Cañada Road||Entrances only|
|||?||Ralph D. Percival Memorial Vista Point||Northbound only|
|||?||Former rest area (closed)||Northbound only|
|||?||Gate Vista Point||Northbound and southbound access|
|||10.87||33||- San Mateo, Hayward, Half Moon Bay||Southbound exit to SR 92 west is via exit 34; SR 92 east exits 8A-B, west exit 8|
|||R12.32||34||south to west / Bunker Hill Drive - Half Moon Bay||South end of SR 35 overlap|
|||R13.10||Crystal Springs Rest Area||Northbound only|
|Hillsborough||R14.22||36||Black Mountain Road, Hayne Road|
|Millbrae||R17.92||40||Millbrae Avenue||Northbound exit and southbound entrance|
|R18.52||41||Larkspur Drive, Millbrae Avenue||Southbound exit and northbound entrance|
|San Bruno||R19.28||north (Skyline Boulevard) - Pacifica||North end of SR 35 overlap; northbound exit and southbound entrance|
|R20.22||42||Crystal Springs Road||Southbound exit and northbound entrance; former SR 117|
|R20.75||43A||San Bruno Avenue||Southbound access is via exit 43B|
|R21.02||43||east to - San Francisco International Airport||Signed as exit 43A southbound, 43B northbound; I-380 exits 5A-B|
|R21.31||43B||Sneath Lane||Northbound access is via exit 43A|
|South San Francisco||R22.04||44||Avalon Drive||Northbound exit and southbound entrance; former SR 117|
|R22.62||45||Westborough Boulevard||Northbound exit as well as southbound entrance from westbound Westborough Blvd. are via exit 44|
|Daly City||R24.20||46||Hickey Boulevard|
|R24.63||47A||Serramonte Boulevard||Southbound exit and northbound entrance|
|R25.28||47B||south - Pacifica||South end of SR 1 overlap; signed as exit 47 northbound; SR 1 north exit 509B|
|R25.78||48||Eastmoor Avenue, Sullivan Avenue||Northbound access is via exit 47|
|M27.17||49A||John Daly Boulevard, Junipero Serra Boulevard||Signed as exit 49 southbound|
|M27.17||49B||north (19th Avenue) - Golden Gate Bridge||North end of SR 1 overlap; northbound left exit and southbound entrance; SR 1 south exit 511|
|City and County of San Francisco|
|R0.74||50||to north / Mission Street, San Jose Avenue||Southbound exit and northbound entrance|
|R1.77||51||Geneva Avenue, Ocean Avenue|
|R2.70||52||Monterey Boulevard||Southbound exit and northbound entrance|
|R2.70||San Jose Avenue||Northbound exit and southbound entrance|
|R3.28||53||Alemany Boulevard, Mission Street|
|R4.34||54A||south (James Lick Freeway) - San Jose||Signed as exit 54 southbound; US 101 north exit 430A|
|R4.34||54B||north (James Lick Freeway) - San Francisco Civic Center, Bay Bridge||Northbound exit and southbound entrance; US 101 south exit 431|
|R5.62||55||Cesar Chavez Street, 25th Street|
|R6.60||56||Mariposa Street, 18th Street|
|T7.54||57||Sixth Street||Northbound exit and southbound entrance|
|T7.26||Fifth Street||At-grade intersection; northern terminus|
|||King Street||Continuation beyond Fifth Street|
|1.000 mi = 1.609 km; 1.000 km = 0.621 mi|