page_title: Interstate 680 (California)
section_title: Route description
hierarchical_section_title: Interstate 680 (California) / Route description
caption_attribution_description: English: Interstate 680 crossing State Route 4, with Mount Diablo rising in backround — in Contra Costa County, northern California. " I'm not a huge fan of the road signage in California. Not that I'm a huge fan of signage in Minnesota, but whatevs. Do I really think that the highway is going to shrink from five lanes to one? Not really."
context_page_description: Interstate 680 is a major north–south auxiliary Interstate Highway in Northern California. It curves around the eastern cities of the San Francisco Bay Area from San Jose to Interstate 80 at Fairfield, bypassing cities along the eastern shore of San Francisco Bay such as Oakland and Richmond while serving others more inland such as Pleasanton and Concord.
  Built in the 1920s and designated in 1955, I-680 begins at a junction with I-280 and US 101, and heads northeast and north-northwest through the northeast part of San Jose. After passing State Route 237 in Milpitas and SR 262 in Fremont, I-680 abruptly turns northeast and enters the hills and valleys of the California Coast Ranges. The highway crosses over Mission Pass, also known as the Sunol Grade, and descends into the Sunol Valley, where it meets SR 84 near Sunol. From Sunol, I-680 again heads north-northwesterly through valleys, including the San Ramon Valley, along the Calaveras Fault. Junctions along this portion include I-580 in Dublin and SR 24 in Walnut Creek.
context_section_description: The route begins at U.S. Route 101 at the Joe Colla Interchange, where it acts as a continuation of I-280 eastward. From here, it begins its journey northward through San Jose, where it meets the Capitol Expressway, signed as CR G21, about a mile northeast of I-680's southern terminus. The next exit northbound is SR 130, which is also known as Alum Rock Avenue, unsigned at the intersection. As it continues through Santa Clara County, it meets numerous local roads before interchanging with the Montague Expressway. Here, it exits San Jose and enters the city of Milpitas, California, where it meets SR 237, often referred to as Calaveras Boulevard. After one more intersection, I-680 exits Santa Clara County and enters Alameda County.
  In Alameda County, the freeway begins in the city of Fremont, where it intersects SR 262, which was unsigned until 2000. Continuing through the city, it meets Mission Boulevard at SR 238 before exiting the city. Prior to 2002, two ghost ramps existed here, remains of an abandoned freeway project replacing Mission Blvd. Amid Alameda County, it abruptly turns northeastward and enters a hilly area, where it crosses over Mission Pass, and descends into the Sunol Valley, where it runs concurrently with SR 84 for a short while. Afterwards, it enters Pleasanton and intersects with I-580, currently California's longest auxiliary interstate providing access to Oakland and the Central Valley. It enters Dublin for a short segment before exiting the county and entering Contra Costa County.
  Upon entering Contra Costa County, the route meets numerous local roads through the cities of San Ramon, Danville, and Alamo before entering Walnut Creek, where it meets SR 24. I-680 then enters Pleasant Hill for a short time and Concord, where it meets SR 242. Upon exiting Concord, it meets SR 4. It then enters Martinez, where it follows the Benicia-Martinez Bridge over the Carquinez Strait, on which the route crosses the county line and enters Benicia in Solano County. On the Benicia-Martinez bridge I-680 northbound is tolled, while I-680 southbound is free. In Benicia, I-680 interchanges with I-780. It then exits the city and after passing through rural areas routing parallel to the San Joaquin Delta, it enters Fairfield, where it meets I-80, which is the route's northern terminus.
  In the wake of the September 11 Attacks, a U.S. flag was painted on a large piece of concrete on a hill along the Sunol Grade. It stayed there for nine years before Caltrans painted it over, as the mural had been painted on without authorization.  Due to this action being taken shortly before July 4th, 2010, and also due to the mural's fame, this was met with controversy. The flag was replaced shortly later. 
  Of the above names, only the name Sinclair Freeway for its designated portion usually appears on maps, and the other portions on maps are always unnamed, referred to as simply I-680.
  I-680 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-680 is eligible to be included in the State Scenic Highway System from the Santa Clara–Alameda county line to SR 24 in Walnut Creek, but is only a scenic route from Mission Boulevard to the Contra Costa county line, and from the Alameda county line to SR 24; this means that those portions are substantial sections of highway passing through a "memorable landscape" with no "visual intrusions", where the potential designation has gained popular favor with the community.
caption: Southbound at SR 4, with Mount Diablo on the left.
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