Interstate 280
I-280 highlighted in red
Route information
Maintained byCaltrans
Length	57.22 mi[1] (92.09 km)
Existed	September 15, 1955, byFHWA[2] July 1, 1964, byCaltrans[3]–present
Tourist routes	Junipero Serra Freeway between the San Mateo–Santa Clara county line andSan Bruno[4]
NHS	Entire route
Major junctions
South end	I-680 /US 101 inSan Jose
Major intersections	SR 87 in San Jose I-880 /SR 17 in San Jose SR 85 inCupertino SR 84 inWoodside SR 92 nearSan Mateo I-380 inSan Bruno SR 1 inDaly City US 101 inSan Francisco
North end	King Street inSan Francisco
Location
Country	United States
State	California
Counties	Santa Clara,San Mateo,San Francisco
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 275 →SR 281

Interstate 280 (I-280) is a 57.22-mile-long (92.09 km) major north–southauxiliary Interstate Highway in theSan Francisco Bay Area ofNorthern California. It runs fromI-680 andUS Route 101 (US 101) inSan Jose to King and 5th streets inSan Francisco, running just to the west of the larger cities ofSan Francisco Peninsula for most of its route.

FromI-880 in San Jose toState Route 1 (SR 1) inDaly City, I-280 was built and dedicated as theJunipero Serra Freeway, after theSpanish Franciscan friar who founded the first nine of 21Spanish missions in California fromSan Diego to San Francisco. One of the dedication signs (in Daly City) still indicates that theJunipero Serra Freeway is known as the "World's Most Beautiful Freeway"^[5] due to its scenic route through the San Francisco Peninsula. From SR 1 to theJames Lick Freeway (US 101) in San Francisco it is officially called theJohn F. Foran Freeway (after a former member of theCalifornia State Legislature). From the James Lick Freeway to its northern end at King and 5th streets, I-280 is called theSouthern-Embarcadero Freeway.

I-280 is one of two auxiliary Interstate designations to appear onopposite coasts of the United States. I-110 inCalifornia andFlorida is the only other designation.

I-280 is shown on the app icon forApple'siOS andmacOS built-inApple Maps. This is because the highway goes throughCupertino, the home of Apple's headquarters. Although the U.S. Route shield is no longer visible on the app icon, the inclusion ofApple Park indicates that the map is centered on the interchange of I-280 and North Wolfe Road.

The entirety of I-280 is defined in section 580 of theCalifornia Streets and Highways Code asRoute 280, and that the highway is from "Route 101 inSan Jose toRoute 80 inSan Francisco viaDaly City".^[6] Route 280 was never fully constructed toI-80, its parent Interstate, as defined. The constructed northernmost segment of I-280 from 6th to 5th streets in San Francisco is also not considered an Interstate Highway according to theFederal Highway Administration (FHWA)'s route logs,^[7][1] but is still signed as such by Caltrans.

The southern end of I-280 is at theJoe Colla Interchange withUS 101 in San Jose, where it acts as a continuation ofI-680 westward.^[8] In between San Jose and San Francisco, I-280 passes throughSanta Clara,Cupertino,Los Altos, andLos Altos Hills before it settles along its scenic route just to the west of the cities of theSan Francisco Peninsula inSan Mateo County and just to the east of theSanta Cruz Mountains. I-280 reemerges in a decidedly urbanized area in the city ofSan Bruno, passing throughSouth San Francisco andDaly 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.^[9][10] Drivers along this portion of I-280 are treated to scenic views of theSanta 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 theSan Andreas Fault. A particularly attractive six-mile (9.7 km) stretch of the freeway fromHillsborough toBelmont provides a view atCrystal Springs Reservoir, formed by water piped over 160 miles (260 km) fromHetch Hetchy Valley inYosemite National Park, partly filling the rift valley. The waters are impounded byCrystal Springs Dam, which drains into San Francisco Bay viaSan Mateo Creek; I-280 crosses the deep valley formed by this creek on theDoran Memorial Bridge, completed in 1969.

• I-280
• 
  Aerial view of I-280 in San Jose, looking northeast toward theJoe Colla Interchange (I-680/US 101) in the distance
• 
  I-280 nearStanford University
• 
  Scenic portion of I-280
• 
  Aerial view directed west showing interchange withSR 92;Crystal Springs Reservoir runs north-south parallel to I-280 through the middle of the photograph

For nearly all of its length, I-280 runs roughly parallel and several miles to the west of US 101 (Bayshore Freeway). Both freeways are north–south routes connecting San Jose with San Francisco; however, unlike I-280, the route that US 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 I-280 and US 101.

Although it wasoriginally intended to do so, I-280 does not intersect withI-80, its parent Interstate. The northern terminus of I-280 is within about a mile (1.6 km) 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 interchanges with the southern ends of I-680 and I-880, both of which connect to I-80 at their northern terminuses. Although San Franciscoplanned 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 theFinancial District, San Francisco, as suggested by signage on northbound US 101 at theAlemany Maze.

Major intersections include US 101 and SR 1 in San Francisco,I-380 in San Bruno,SR 92 inSan Mateo, SR 85 in Cupertino, andI-880 and I-680 and US 101 in San Jose.

I-280 is part of theCalifornia Freeway and Expressway System^[11] and is part of theNational Highway System,^[7] a network of highways that are considered essential to the country's economy, defense, and mobility by theFederal Highway Administration (FHWA).^[12] I-280 is eligible for theState Scenic Highway System^[13] and, from the San Mateo–Santa Clara county line to the San Bruno city limits, is officially designated as a scenic highway by theCalifornia Department of Transportation (Caltrans),^[14] 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.^[15] The Junipero Serra Freeway is the name of I-280 from SR 1 in San Francisco toSR 17, as named by Assembly Concurrent Resolution 140, Chapter 208 in 1967, in honor of Spanish missionaryJunípero Serra, who founded many ofCalifornia's missions in the 18th century. I-280 from its southern terminus at US 101 and I-680 north to I-880 in San Jose is part of theSinclair Freeway (named after Joseph P. Sinclair, District Engineer for District 4 California Division of Highways).^[16][17][18] A 26-foot (7.9 m) high faux-sandstone statue of Serra was placed at the Crystal Springs Rest Area in 1975.^[19] Visible in both directions from the highway, it was removed by Caltrans in 2025. According to an official statement, "The installation did not meet current Transportation Art Program requirements and had been afrequent target of graffiti and vandalism."^[20]

TheSLAC National Accelerator Laboratory, a research center operated byStanford University, houses a 2-mile-longlinear accelerator that extends underground, running 30 feet below I-280 near theSand Hill Road exit in Menlo Park.^[21][22]

I-280 was added to theInterstate Highway System on September 15, 1955, as a route fromSan Jose north toSan Francisco. This ran along the present alignment of I-280 south of San Francisco, but, in San Francisco, it was instead intended to run north parallel toSR 1, past the planned west end ofI-80 which would have been at the junction with thePanhandle Freeway just south ofFulton and Park Presidio, along what would have been the Park Presidio Freeway north to the south approach to theGolden Gate Bridge. At that point, I-280 would have metI-480 (Embarcadero Freeway), which would have headed east onDoyle Drive (US 101), theGolden Gate Freeway, and onto the Embarcadero Freeway to reach theSan 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 streets, then along the present Southern-Embarcadero Freeway to meet the Southern Freeway (now I-280) near theAlemany Maze, which served as theUS 101 Bypass until I-280 was built. The I-280 number was approved on November 10, 1958.^[2]

In the1964 renumbering, I-280's legislative 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 atSR 82 (San Jose Avenue/Alemany Boulevard). SR 1, however, continued to be signed along its former (and current) alignment, which had not been upgraded tofreeway standards.

A realignment approved January 1968 primarily took I-280's legislative definition onto its current route. This new routing ran along what had been SR 1, SR 82,SR 87, and I-480 (downgraded toSR 480 then), ending atI-80 at the western Bay Bridge approach.^[2] 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.^[3]

For the scenic portion, the section of I-280 between SR 85 (Cupertino) and SR 84 (Woodside) was completed in the late 1960s alongside SR 85. 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.^{[citation needed]}

A direct freeway connection between I-280 and I-80 was never completed. I-280 was planned to run alongThe Embarcadero underneath the Bay Bridge approach/I-80 to connect to SR 480 and then loop back to the Bay Bridge approach/I-80 near 1st Street.^[3] The segment of I-280 between 3rd Street and SR 480 was never built, leaving the I-280 structure terminating in midair at 3rd Street, withramp stubs at 5th Street that were intended to connect to aparallel bay bridge (also not built). This caused the completed freeway segment from the Bay Bridge approach/I-80 near 1st Street to The Embarcadero to be signed as part of SR 480 instead of I-280.^[3][23] After the1989 Loma Prieta earthquake, plans to connect I-280 to I-80 were abandoned, the earthquake-damaged Embarcadero Freeway was torn down in 1991, and the north end of I-280 was reconfigured to the present-day King Street on/offramps in 1997.^[3]

The interchange at the beginning of I-280 at I-680 and US 101 in San Jose was built years before its completion. The three flyovers, with no connecting ramps, stood as a 110-foot-tall (34 m) monument to inefficiency for years in the 1970s, becoming the butt of jokes. The highlight prank occurred in January 1976, when a1960 Chevrolet Impala was placed on the highest bridge overnight, where it obviously would be impossible to drive. The following day, San Jose City Councilmember Joe Colla was photographed standing next to the car, an image that appeared in many newspapers.^[24][25] 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 theJoe Colla Interchange in memory of the late councilmember.^[26]

In 2021University of California, Davis, researchers published a report onwildlife-vehicle collisions based onCalifornia Highway Patrol and insurance data over the past five years, according to which five of the 20 one-mile (1.6 km) stretches of highway in the state with the highest costs for this reason are on I-280, the worst being between San Bruno and Cupertino.^[27]

County	Location	mi[28][29][30][31]	km	Exit[28]	Destinations	Notes
Santa Clara	San Jose	0.00	0.00	—	I-680 north (Sinclair Freeway) –Sacramento	Southern terminus;Joe Colla Interchange; US 101 north exit 384, south exit 385B; Sinclair Freeway continues east as I-680 north
				—	US 101 north (Bayshore Freeway) –San Francisco
				—	US 101 south (Bayshore Freeway) –Los Angeles
		0.36	0.58	1A	McLaughlin Avenue	Southbound exit and northbound entrance
		1.29	2.08	1B	11th Street, 10th Street	Signed as exit 1 northbound
		1.55	2.49	2A	7th Street, Virginia Street toSR 82	Signed as exit 2 northbound; Virginia Street not signed northbound
		2.20	3.54	2B	Almaden Boulevard, Vine Street	Southbound exit and northbound entrance
		2.52	4.06	3A	SR 87 (Guadalupe Parkway)	SR 87 exit 5
		2.88	4.63	3B	Bird Avenue
		3.88	6.24	4	Race Street, Southwest Expressway	Northbound exit and southbound entrance
		3.99	6.42		Meridian Avenue	Southbound exit and northbound entrance
		4.99	8.03	5A	Leigh Avenue, Bascom Avenue
		5.41	8.71	5B	I-880 north (Nimitz Freeway) /SR 17 south –Oakland,Santa Cruz	West end of the Sinclair Freeway, south end of Junipero Serra Freeway; SR 17 north exits 27A-B; I-880 south exit 1B
		5.41	8.71	5C	Stevens Creek Boulevard, West San Carlos Street	Northbound exit and southbound entrance
		5.95	9.58	6	Winchester Boulevard	Southbound exit and northbound entrance
		7.33	11.80	7	Saratoga Avenue –Saratoga
		8.51	13.70	9	Lawrence Expressway (CR G2), Stevens Creek Boulevard
	Cupertino	9.76	15.71	10	Wolfe Road
		10.82	17.41	11	De Anza Boulevard	FormerSR 85
		12.12	19.51	12A	SR 85 north –Mountain View	SR 85 north exit 19, south exit 19A
		12.12	19.51	12B	SR 85 south –Santa Cruz,Gilroy
	Los Altos	12.83	20.65	13	Foothill Expressway (CR G5), Grant Road
	​	15.48	24.91	15	Magdalena Avenue
	Los Altos Hills	16.43	26.44	16	El Monte Road, Moody Road
	​	19.76	31.80	20	Page Mill Road (CR G3), Arastradero Road –Palo Alto	Arastradero Road not signed northbound; Palo Alto not signed southbound
	​	22.00	35.41	22	Alpine Road –Portola Valley
San Mateo	​	23.62	38.01	24	Sand Hill Road
	Woodside	25.34	40.78	25	SR 84 (Woodside Road)
		26.65	42.89	27	Farm Hill Boulevard
		28.60	46.03	—	Cañada Road	Entrances only
	​	28.66	46.12	29	Edgewood Road
	​			Ralph D. Percival MemorialVista Point (northbound only)
	​			Formerrest area (northbound only; closed)
	​			Gate Vista Point
	​	32.84	52.85	33	SR 92 –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
	​	34.33	55.25	34	SR 35 south toSR 92 west / Bunker Hill Drive –Half Moon Bay	South end of SR 35 overlap
	San Mateo Creek	35.27	56.76	Doran Memorial Bridge
	​	35.43	57.02	Crystal SpringsRest Area (northbound only)
	Hillsborough	36.24	58.32	36	Black Mountain Road, Hayne Road
	​	39.17	63.04	39	Trousdale Drive
	Millbrae	39.67	63.84	40	Millbrae Avenue	Northbound exit and southbound entrance
		40.53	65.23	41	Larkspur Drive, Millbrae Avenue	Southbound exit and northbound entrance
	San Bruno	41.29	66.45		SR 35 north (Skyline Boulevard) –Pacifica	North end of SR 35 overlap; northbound exit and southbound entrance
		42.28	68.04	42	Crystal Springs Road	Southbound exit and northbound entrance; formerSR 117
		42.75	68.80	43A	San Bruno Avenue, Sneath Lane	Southbound exit and northbound entrance
		42.75– 43.02	68.80– 69.23	43	I-380 east toUS 101 –San Francisco International Airport	Signed as exit 43A southbound, 43B northbound; I-380 exits 5A-B
		43.02	69.23	43B	Sneath Lane, San Bruno Avenue	Northbound exit and southbound entrance
	South San Francisco	44.05	70.89	44	Avalon Drive, Westborough Boulevard	Northbound exit and southbound entrance; formerSR 117
		44.63	71.83	45	Westborough Boulevard	Northbound exit as well as southbound entrance from westbound Westborough Blvd. are via exit 44
	Daly City	46.20	74.35	46	Hickey Boulevard
		46.83	75.37	47A	Serramonte Boulevard	Southbound exit and northbound entrance
		47.29	76.11	47	SR 1 south / Eastmoor Avenue –Pacifica	Northbound signage; SR 1 north exits 509B and 510
				47B	SR 1 south –Pacifica	Southbound signage; south end of SR 1 overlap; SR 1 north exit 509B
		47.78	76.89	48	Eastmoor Avenue, Sullivan Avenue	Southbound exit and northbound entrance
		48.51	78.07	49A	John Daly Boulevard,Junipero Serra Boulevard	Signed as exit 49 southbound
		49.17	79.13	49B	SR 1 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 ofSan Francisco		50.18	80.76	50	SR 82 toSR 1 north /Mission Street, San Jose Avenue	Southbound exit and northbound entrance
		51.21	82.41	51	Geneva Avenue, Ocean Avenue
		52.13	83.90	52	Monterey Boulevard	Southbound exit and northbound entrance
		52.14	83.91		San Jose Avenue, Bosworth Street	Northbound exit and southbound entrance
		52.72	84.84	53	Alemany Boulevard,Mission Street	Mission Street not signed northbound
		53.78	86.55	54A	US 101 south (James Lick Freeway) –San Jose	Southern end ofAlemany Maze; signed as exit 54 southbound; US 101 north exit 430A
		53.78	86.55	54B	US 101 north (James Lick Freeway) –San Francisco Civic Center,Bay Bridge	Northbound exit and southbound entrance; northern end ofAlemany Maze; US 101 south exit 431
		55.06	88.61	55	Cesar Chavez Street, 25th Street	25th Street not signed northbound; Cesar Chavez Street was formerly Army Street
		56.04	90.19	56	Mariposa Street, 18th Street	18th Street not signed northbound
		56.73	91.30	57	Sixth Street	Northbound exit and southbound entrance
		56.98	91.70	—	Fifth Street	At-grade intersection; northern terminus
				—	King Street	Continuation beyond Fifth Street
				—	Fourth Street	Former northern terminus; replaced with the current King Street ramps; northbound exit only
1.000 mi = 1.609 km; 1.000 km = 0.621 mi       Closed/former       Concurrency terminus       Incomplete access       Route transition

• California Roads portal
• San Francisco Bay Area portal

Wikimedia Commons has media related toInterstate 280 (California).

• Caltrans: I-280 highway conditions
• Caltrans Traffic Conditions Map
• California Highway Patrol Traffic Incidents
• AARoads – Interstate 280
• Planning maps for the pre-1968 planned route of the freeway along Junipero Serra Boulevard in San Francisco
• California Highways: I-280
• Freeways not built in S.F.

• Interstate Highways in California
• San Francisco Bay Area freeways
• Auxiliary Interstate Highways
• Interstate 80
• Roads in Santa Clara County, California
• Roads in San Mateo County, California
• Roads in San Francisco
• State Scenic Highway System (California)
• Transportation in Sunnyvale, California
• Junípero Serra

• CS1 location test
• Articles with short description
• Short description is different from Wikidata
• Use mdy dates from December 2022
• Use American English from December 2022
• All Wikipedia articles written in American English
• Infobox road instances in California
• All articles with unsourced statements
• Articles with unsourced statements from February 2008
• Commons category link from Wikidata
• Pages using gadget WikiMiniAtlas
• Articles using KML from Wikidata
• Pages using the Kartographer extension