About the county:

Contra Costa County is a primarily suburban county in the San Francisco Bay Area of the U.S. state of California.

 

Incorporated and unincorporated cities include: El Cerrito, Hercules, Pinole, Richmond, San Pablo, Bayview-Montalvin, Crockett, East Richmond Heights, El Sobrante, Kensington, North Richmond Port Costa, Rodeo Rollingwood, Tara Hills, Central County, Clayton, Concord ,Danville, Lafayette, Martinez, Moraga, Orinda, Pleasant Hill, San Ramon, Walnut Creek, Alamo, Blackhawk-Camino Tassajara, Canyon, Clyde, Diablo, Mountain View, Pacheco, Vine Hill, Waldon, East County, Antioch, Brentwood, Oakley, Pittsburg, Bay Point, Bethel Island, Byron, Discovery Bay, and Knightsen.