About: California State Route 123

State Route 123 (SR 123) is a 7.39-mile (11.89 km) state highway in the U.S. state of California in the San Francisco Bay Area. Named San Pablo Avenue for almost its entire length except for its northernmost 0.10 miles (0.16 km), SR 123 is a major north–south state highway along the flats of the urban East Bay. Route 123 runs between Interstate 580 in Oakland in the south and Interstate 80 at Cutting Boulevard in Richmond in the north. San Pablo Avenue itself, a portion of Historic US 40, continues well past the SR 123 designation south to Downtown Oakland and north to Crockett.