Contra Costa County was incorporated in 1850 as one of the original 27 counties of the State of California 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 is the ninth most populous county in California, with its population reaching approximately 930,000 as of January 1, 2000.  The County has one of the fastest growing work forces among Bay Area counties, with growth in its employment base being driven primarily by the need to provide services to an increasing local population.  Due to the presence of relatively high-wage skilled jobs and relatively wealthy residents, the County achieves high rankings among all California counties on a variety of income measurements.

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 Bay Area Rapid Transit District (BART), which has encouraged 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.