About: California State Route 123

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.