Reference 1: Population (2010 Census).
Reference 2: Concord, Richmond, Antioch, San Ramon, Walnut Creek, Pittsburg, Brentwood, Danville, † Martinez, Oakley, Pleasant Hill, San Pablo, Hercules, Lafayette, El Cerrito, Bay Point, Pinole, Orinda, Moraga, Alamo, Discovery Bay, El Sobrante, Clayton, Blackhawk, Rodeo, Contra Costa Centre, Saranap, Tara Hills, Kensington, Vine Hill, North Richmond, Pacheco, San Miguel, East Richmond Heights, Reliez Valley, Crockett, Rollingwood, Montalvin Manor, Mountain View, Camino Tassajara, Bethel Island, Bayview, Knightsen, Castle Hill, Byron, Diablo, Acalanes Ridge, Shell Ridge, Norris Canyon, Alhambra Valley, North Gate, Clyde and Port Costa.
Source: http://en.wikipedia.org/wiki/Contra_Costa_County,_California
Reference 2: Concord, Richmond, Antioch, San Ramon, Walnut Creek, Pittsburg, Brentwood, Danville, † Martinez, Oakley, Pleasant Hill, San Pablo, Hercules, Lafayette, El Cerrito, Bay Point, Pinole, Orinda, Moraga, Alamo, Discovery Bay, El Sobrante, Clayton, Blackhawk, Rodeo, Contra Costa Centre, Saranap, Tara Hills, Kensington, Vine Hill, North Richmond, Pacheco, San Miguel, East Richmond Heights, Reliez Valley, Crockett, Rollingwood, Montalvin Manor, Mountain View, Camino Tassajara, Bethel Island, Bayview, Knightsen, Castle Hill, Byron, Diablo, Acalanes Ridge, Shell Ridge, Norris Canyon, Alhambra Valley, North Gate, Clyde and Port Costa.
Source: http://en.wikipedia.org/wiki/Contra_Costa_County,_California
