California State Route 123

State Route 123
San Pablo Avenue
Map of California's San Francisco Bay Area with SR 123 highlighted in red
Route information
Defined by
Maintained by Caltrans
Length:	7.375 mi (11.869 km)
Major junctions
South end:	I-580 in Oakland
	SR 13 in Berkeley
North end:	I-80 in Richmond
Highway system
State highways in California Interstate U.S. State Pre-1964 History Unconstructed Deleted Freeway Scenic ← SR 121 SR 124 →

State Route 123 (SR 123) is a state highway in the U.S. state of California in the San Francisco Bay Area. Named San Pablo Avenue for virtually its entire length, SR 123 is a major north–south state highway along the flats of the urban East Bay in the U.S. state of California. Route 123 runs a relatively short 7.39 miles (11.9 km) between Interstate 580 in the south and Interstate 80 in the north. San Pablo Avenue itself, a portion of Historic US 40, continues well past these termini but without the Route 123 designation.

Route 123 is a four-lane boulevard with a median strip for its entire length. Its southern terminus is at the underpass of Interstate 580 in Oakland. Going north, it passes through the cities of Emeryville, Berkeley, Albany, El Cerrito. It briefly turns on Cutting Boulevard before entering Richmond at its northern terminus under Interstate 80.

San Pablo Avenue is sometimes used as an alternate route to the Eastshore Freeway (Interstate 80) when that freeway becomes very congested. Major intersections along this route include 40th Street, Ashby Avenue (State Route 13), University Avenue (which leads to UC Berkeley), Gilman Street, Marin Avenue, Central Avenue and Cutting Boulevard.