In prehistoric times, particularly the Miocene epoch, portions of the landforms now in the area (then marshy and … See more

According to the U.S. Census Bureau, the county has a total area of 804 square miles (2,080 km ), of which 716 square miles (1,850 km ) is land and 88 square miles (230 km ) (11%) is water.
Contra Cos… See more

Note: the US Census treats Hispanic/Latino as an ethnic category. This table excludes Latinos from the racial categories and assigns them to a separate category. Hispanics/Latinos can be of any race.
The … See more

Since 1932, Contra Costa County has been a Democratic stronghold in presidential elections. It temporarily leaned toward the Republican Party in the 1970s and 1980s, with successive presidential wins by Richard Nix… See more

The great rancheros of the Spanish period were divided and sold for agricultural uses, with intensively irrigated farming made possible in some areas by the development of canals that brought water from the eastern riv… See more

The Contra Costa County Library is the county's library system. See more

Contra Costa County receives media from the rest of the Bay Area.
The City of Concord is served by the daily newspaper, the East Bay Times published by the Bay Area News Group-East Bay (part of the … See more