The County of Contra Costa, California (the "County") was incorporated in 1850 as one of the original 27 counties of the State of California (the "State"), with the City of Martinez as the County Seat.

It is one of the nine counties in the San Francisco-Oakland Bay Area. The County covers about 733 square miles and extends from the northeastern shore of San Francisco Bay easterly about 50 miles to San Joaquin County. The County is bordered on the south and west by Alameda County and on the north by Suisun and San Pablo Bays. The western and northern shorelines are highly industrialized, while the interior sections are suburban/residential, commercial and light industrial. The County contains 19 incorporated cities, including Richmond in the west, Oakley in the northeast, and Concord in the middle.

A large part of the County is served by the San Francisco Bay Area Rapid Transit District ("BART"), which has enabled the expansion of both residential and commercial development. In addition, economic development along the Interstate 680 corridor in the County has been substantial and has accounted for significant job creation in the Cities of Concord, Walnut Creek and San Ramon.

Cities in Contra Costa County

The County consists of the following cities: Antioch, Brentwood, Clayton, Concord,  Danville, El Cerrito, Hercules, Knightsen, Lafayette, Oakley, Orinda, Pinole,  Pittsburg, Pleasant Hill, Richmond, San Pablo, San Ramon and Walnut Creek.

 Source: Contra Costa County Government   http://www.co.contra-costa.ca.us/