California 37


This California 37 east reassurance shield is posted near Sears Point east of Novato. Photo taken 11/26/04.

California 37 is a major route connecting the cities of the North Bay. Starting at U.S. 101 in Novato, California 37 carries two to four lanes across the marshy flats that define the northern shore of the San Francisco (San Pablo) Bay. The highway intersects California 121 at Sears Point, then swings southeast into Vallejo. Passing to the north of that city, California 37 again changes into a expressway/freeway combination as it connects with California 29 and Interstate 80.

With a spate of accidents and injuries in the 1990s, California 37 carried the inglorious moniker "Blood Alley," resulting in a higher priority for local politicians to find funding to make California 37 into an expressway and ultimately as a freeway. Currently, sections of California 37 slated for such an expansion, especially in Vallejo, where a new interchange is planned with California 29. The stretch along the marshy north shore is also slated for expansion, but such work requires extensive environmental review due to the preponderance of wetlands in the vicinity.

Historically, California 37 was more of a north-south route than east-west route. It used to follow the path now taken by California 121, coming to its northern terminus at California 128 near Lake Berryessa. California 48 covered the stretch of California 37 from Sears Point east to Vallejo. However, in an effort to streamline the north shore corridor with one number, California 37 was rerouted onto former California 48, and it became more of an east-west rather than north-south route. The California 48 designation was transferred to a proposed east-west freeway in the Antelope Valley near Lancaster/Palmdale; the freeway has not yet been constructed.

Highway Guide

California 37 scenes
From the California 37 Petaluma River bridge, this view look south as the river enters San Pablo Bay, as well as a nearby railroad bridge over the river and a distant PG&E power line tower. Photo taken 11/26/04.
Some traffic reporters refer to the nine bridges of the San Francisco Bay Area. Some of the bridges are easily identifiable, including the Golden Gate Bridge (U.S. 101) and San Francisco-Oakland Bay Bridge (Interstate 80). A few are on a second tier of trans-bay bridges that are less well-known than those two, including California 84 (Dumbarton Bridge), California 92 (San Mateo Bridge), and Interstate 580 (Richmond-San Rafael Bridge). Then there are the three Delta bridges: Interstate 80 (Carquinez/Alfred Zampa Bridges), Interstate 680 (Benicia-Martinez Bridge), and California 160 (Antioch Bridge). That accounts for eight of the nine bridges, and they all carry a common thread of being toll bridges. But when reporters mention that ninth bridge, they are referring to the California 37/Mare Island Bridge, which is visible to the northwest from this vantage point along Wilson Avenue northbound in Vallejo. Photo taken 04/02/04.
The Mare Island Bridge is a high bridge that crosses over the Napa River and allows clearance for tall ships to make their way under the bridge, including those vessels en route to the closed Mare Island Naval Reservation. A smaller lift bridge just to the south of this high bridge provides direct access to the former naval reservation. This picture looks southwest at the bridge from Wilson Avenue as it passes under California 37. Photo taken 04/02/04.
Southbound Wilson Avenue enters Vallejo Heights just south of the California 37 Mare Island Bridge. Photo taken 04/02/04.
Northbound Wilson Avenue approaches its junction with California 37 near the eastern end of the Mare Island Bridge. Photo taken 04/02/04.


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Page Updated November 29, 2011.

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