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Interstate 280 California


Often referred to as one of the most scenic urban freeways in America, Interstate 280 (Junipero Serra Freeway and Sinclair Freeway) comprises both an alternate and commuter route from San Francisco to San Jose. Bypassing the more industrial and crowded U.S. 101, Interstate 280 is eight lanes throughout, following the San Andreas fault line along the San Francisco peninsula.

Originally planned to connect to Interstate 80 near the San Francisco-Oakland Bay Bridge, Interstate 280 ends just shy of this canceled interchange and the parent route. It used to extend as far as Third Street, but now terminates just south of the new AT&T Ballpark (home of the MLB San Francisco Giants), where it transitions onto King Street and ultimately the Embarcadero. There are no current plans to construct the remainder of I-280 at this time, but it remains as a proposed route on the Caltrans map.

The 1968 California Official Map indicated that Temporary alignments for Interstates 280 and 680 followed California 17 (I-880 today) through San Jose before the two freeways were completed.


A victim of the San Francisco Freeway Revolt of the 1960s, Interstate 280 was originally proposed to have a much different northern terminus. As displayed on the 1964 Official California State Map, the section of modern Interstate 280 between California 82 and Interstate 80 was planned to be signed as a northern extension of California 82 and California 87. I-280 meanwhile was proposed to continue north roughly parallel to the California 1 (19th Avenue) corridor. It was to follow Junipero Serra Boulevard, Portola Drive and Seventh Avenue, then skirt the eastern edge of Golden Gate Park, where Interstate 280 was to have met a western extension of I-80. Continuing north, I-280 would have followed Park Presidio Boulevard north into the Presidio. Interstate 280 would have ended at the southern end of the Golden Gate Bridge, where U.S. 101 would continue north to Marin County and Interstate 480 would turn east along the unconstructed Golden Gate Freeway and demolished Embarcadero Freeway to rejoin Interstate 80. This in effect would have created a belt freeway system for San Francisco.

However, between 1965 and 1968, San Francisco city government decided not to construct most of the freeway system. Only stubs of California 480 and U.S. 101 touched the city, but neither freeway connected to any other freeway. The unbuilt section of Interstate 280 was not constructed at all prior to the revolt, so it was dropped from the plans in its entirety. As a result, I-280 was rerouted onto the California 82 corridor north to U.S. 101 and California 87 from there to Interstate 80.

Highway Guides

Southern Terminus - Interstate 680/U.S. 101 - San Jose, California
Perspective from Interstate 280 south
Interstate 280 southbound (actually east at this point) approaching the stack interchange with Interstate 680 and U.S. 101. Photo taken 12/27/01.
Interstate 280 southbound (actually east at this point) approaching McLaughlin Avenue and the stack interchange with Interstate 680 and U.S. 101. The overhead signage now reads Interstate 680 rather than 280, but 280 does not end until the interchange itself. Photo taken 12/27/01.
Interstate 280 southbound (actually east at this point) at McLaughlin Avenue approaching the U.S. 101 interchange. Photo taken 12/27/01.
Interstate 280 southbound ends at this point under the U.S. 101 stack interchange. Northbound Interstate 680 begins here. No end Interstate 280 signage is present. Photo taken 12/27/01.
Perspective from Interstate 680 south
The first sign of the pending interchange between Interstate 680 and U.S. 101 appears on this interchange sequence sign at the Capitol Expressway on-ramp. Photo taken 03/27/16.
Interstate 680 turns southwest between the Mayfair and Arbuckle communities to King Road (Exit 1C). A double lane drop follows the King Road exit for the flyover ramps to U.S. 101 (Bayshore Freeway). Photo taken 11/29/04.
Interstate 680 south maintains four through lanes for the continuation onto Interstate 280 north. Three lanes depart otherwise for U.S. 101 north to Santa Clara, Sunnyvale and San Francisco and south to Santa Teresa, Salinas and Los Angeles. Photo taken 11/29/04.
The interchange between Interstate 680, Interstate 280, and U.S. 101 is a four-level cloverstack, with flyover ramps handling most of the movements. The ramp from southbound Interstate 680 to southbound U.S. 101 is visible here. The confirming shield here is the first one for northbound Interstate 280. Photo taken 11/29/04.
Perspective from U.S. 101 north
U.S. 101 advances one mile north to the cloverstack interchange (Exit 384) with Interstate 280 north to Downtown San Jose and Interstate 680 north to Fremont and Walnut Creek. Photo taken 03/25/16.
Interchange sequence sign posted 0.75 miles ahead of the ramp departure (Exit 384) for I-280 and I-680 north. The forthcoming flyover passes above the cloverleaf interchange with Story Road (Exit 385). Photo taken 03/25/16.
U.S. 101 north expands to six lanes with an auxiliary lane gained from Tully Road. A two-lane off-ramp (Exit 384) follows for Interstates 280 and 680 north. Photo taken 03/25/16.
Traffic departs U.S. 101 north for Exit 384 ahead of Story Road. Interstate 280 north arcs southwest toward Downtown San Jose, then north to Daly City and San Francisco. Interstate 680 north travels to Fremont, then angles northeast via the Sunol Grade to Pleasanton/Dublin and onward to the San Ramon Valley. Photo taken 03/25/16.
Historic Perspective from U.S. 101 north
This set of button copy signs for I-280 & 680 and Tully Road was replaced by 2013 to incorporate exit numbers. Photo taken 12/23/04.
Perspective from U.S. 101 south
This mileage sign provides the distance to Exit 385B, Interstate 280 north to downtown San Jose and Interstate 680 north to Fremont and Walnut Creek. Photo taken 11/29/04.
Prior to reaching Interstate 280 and Interstate 680, U.S. 101 southbound first reaches Exit 386A, California 130/Alum Rock Avenue. California 130 is planned as an potential freeway route between San Jose and the Central Valley, but for now California 130 is a twisty road to Mount Hamilton that does not meet Interstate 5. Photo taken 11/29/04.
Southbound U.S. 101 reaches Exit 386A, California 130/Alum Rock Avenue. The next exit is Exit 385B, Interstate 280 and Interstate 680. Photo taken 11/29/04.
Southbound U.S. 101 approaches Exit 385B, Interstate 280 and Interstate 680. Although marked as north, Interstate 280 actually travels west through Silicon Valley briefly before it turns north toward San Francisco. Interstate 680 is signed with Sacramento as its control city, but it passes through several major cities including Pleasanton, Walnut Creek, and Concord along the way. Photo taken 11/29/04.
The right two lanes of southbound U.S. 101 connect to Interstate 280 north and Interstate 680 north. The left four lanes continue south on U.S. 101, which is signed with a control city of Los Angeles. Photo taken 11/29/04.
Southbound U.S. 101 reaches Exit 385B, Interstate 280 and Interstate 680. This is one of the rare instances where a three-digit Interstate route with an even first number ends at a non-Interstate. Other examples include Interstate 264 in Virginia Beach, Virginia, and Interstate 635 northwest of Dallas, Texas. Photo taken 11/29/04.
View of the Interstate 280/Interstate 680 stack interchange as seen along southbound U.S. 101 in San Jose. Photo taken 11/29/04.
Northern Terminus - King Street - San Francisco, California
Perspective from Interstate 280 South
Westbound King Street approaches Fifth Street, the final traffic signal prior to transitioning onto Interstate 280 southbound. Photo taken 11/26/04.
The northern terminus of Interstate 280 is in the vicinity of SBC Park, where Major League Baseball's San Francisco Giants play. This sign assembly indicates the transition of the southbound Embarcadero (King Street) onto Interstate 280. Freeway entrances are located just beyond the stoplight, and the viaduct carries traffic to U.S. 101 and beyond. Photo taken 10/16/00.
The freeway begins without even a trailblazer for Interstate 280, just the freeway entrance shield after the Fifth Street traffic signal. Photos taken 11/26/04.
Southbound Interstate 280 begins as a viaduct, carrying the freeway high above the neighborhoods of Mission Bay and Potrero Hill. As a result of damage sustained after the Loma Prieta Earthquake of 1989, the Interstate 280 viaduct between Fifth Street and U.S. 101 was reconstructed. Photo taken 10/16/00.
After traffic from Sixth Street merges onto southbound Interstate 280, the first exit is Exit 56, Mariposa Street and 18th Street in Potrero Hill. Photo taken 11/26/04.
Southbound Interstate 280, approaches Exit 55, Cesar Chavez (Army) Street. The next exit is the connection to southbound U.S. 101. There is no connection to northbound U.S. 101. Interstate 280 assumes a double decker configuration south of the Cesar Chavez Street interchange until the U.S. 101 transition ramp. Photo taken 11/26/04.
Now on the top deck of the double decked section of freeway, the left lane becomes exit only for U.S. 101 south to San Jose, while the two right lanes are signed for Interstate 280 south to Daly City and Pacifica. Interstate 280 is also a less congested route to San Jose. Photo taken 11/26/04.
Perspective from Interstate 280 north
Northbound Interstate 280 approaches U.S. 101, the Bayshore Freeway. This is the last freeway-to-freeway interchange along northbound. Despite its numbering, Interstate 280 does not connect directly with Interstate 80. To reach Interstate 80 and the Bay Bridge, use U.S. 101 north. Even though the northern terminus of Interstate 280 at 6th Street and King Street is mere blocks from Interstate 80, there is no freeway to freeway connection from Interstate 280 north to Interstate 80. Photo taken 11/26/04.
Interstate 280 splits with U.S. 101, with U.S. 101 northbound offering the only freeway to freeway connection to Interstate 80. Note the control city of Bay Bridge; it would be helpful if there were also an Interstate 80 shield posted here. Photo taken 11/26/04.
After the U.S. 101 interchange, northbound Interstate 280 changes into a double-decked, elevated freeway. The northbound lanes form the lower deck, while the southbound lanes follow the top deck of the freeway. Photo taken 11/26/04.
At the Cesar Chavez Street (former Army Street) off-ramp, Interstate 280 reverts to a traditional elevated freeway. The control city for Interstate 280 is Sixth Street, while some auxiliary signs mention SBC Park, a Major League ballpark located near the northern end of the freeway on King Street. Photo taken 11/26/04.
The next exit along northbound is Exit 56, Mariposa Street. The towers of the San Francisco-Oakland Bay Bridge, which carries Interstate 80 over the San Francisco, are visible in the distance. From here, the best route to the bridge is via the northbound Sixth Street exit, then turning right onto Bryant Street. This distance is only about four blocks, but it can take a bit of time to make the connection during heavy commuting periods. Photo taken 11/26/04.
Just prior to the Mariposa Street off-ramp, this sign advises motorists of when there is heavy traffic or delays on King Street (near SBC Park). During those peak periods, traffic is advised to use Sixth Street instead. Photo taken 11/26/04.
After Exit 56 (Mariposa Street), the next exit is Exit 57, Sixth Street. The two left lanes continue north on Interstate 280 to King Street, while the right lanes exit only to Sixth Street. Photo taken 11/26/04.
The skyline of downtown San Francisco comes into view as Interstate 280 turns northwest as it approaches Exit 57, Sixth Street. Photo taken 11/26/04.
On a clear day, the view of northbound Interstate 280 as it approaches downtown one of the most scenic urban freeways. Other stretches of Interstate 280 between San Jose and San Francisco traverse some beautiful rural areas. Photo taken 10/16/00.
The two left lanes continue along Interstate 280 north to King Street, while the two right lanes connect directly onto Sixth Street north to Interstate 80/Bay Bridge. However, there is no signage anywhere at the north end of Interstate 280 that directs motorists to Interstate 80. Photo taken 11/26/04.
Northbound Interstate 280 reaches Exit 57, Sixth Street north to Interstate 80/Bay Bridge. The left two lanes will feed directly into King Street near SBC Park, even though King Street is not signed on the overhead signs here. Photo taken 11/26/04.
After the Sixth Street off-ramp, Interstate 280 prepares to end, as the viaduct descends to ground level. Traffic that continues straight ahead will be dropped onto King Street, which runs parallel to Interstate 80, a few blocks to the north. King Street feeds directly into the Embarcadero, and it turns along the bayshore to connect with Fisherman's Wharf and downtown. Photo taken 11/26/04.
Northbound Interstate 280 approaches its end as it passes under the flyover ramp to Sixth Street. Photo taken 11/26/04.
Interstate 280 reaches its northern terminus as the freeway smoothly transitions onto King Street. The first signal ahead is Fifth Street; SBC Park is only two blocks further east on King Street, at the intersection with Third Street. Interstate 280 was retracted a few blocks west of its former northern terminus as a result of earthquake damage and redevelopment in the vicinity of the ballpark. Eastbound King Street transitions directly into the Embarcadero, which offers a direct connection to the many bayside attractions that San Francisco has to offer, including Rincon Point, the Ferry Building, Pier 39, and Fisherman's Wharf. Photo taken 11/26/04.
Northbound Interstate 280 ends here at the Fifth Street intersection. King Street continues straight ahead from here. There is no end shield present. Photo taken 11/26/04.

Page Updated April 6, 2016.

State California
Mileage 57.22
Cities San Jose, Daly City, San Bruno, Mountain View, San Francisco
Junctions I-680, I-380
Source: December 31, 2018 Interstate Route Log and Finders List
I-280 California Annual Average Daily Traffic
Location AADT Composite
San Jose 228,000
Cupertino 150,000
Millbrae 110,000
South San Francisco 180,000
Daly City 223,000
San Francisco 191,000
San Francisco 86,000
Source: Caltrans, Traffic Operations Program - Traffic and Vehicle Data Systems [2002]
The east-west portion of Interstate 280 between California 17 and U.S. 101 opened to traffic in mid 1972.
The south end of Interstate 280 defaulted traffic to U.S. 101 (Bayshore Freeway) until September 4, 1974, when I-680 was completed through San Jose.
Interstate 280 designated as California 82 (Southern Freeway) in 1965.
Interstate 280 was added along side California 82 in San Francisco in 1965 and dropped along the freeway in 1968.