Welcome to Contra Costa County

Contra Costa County has over one million residents and one of the first 27 counties established in California in 1850. Contra Costa has 19 cities and several outlying communities in the unincorporated rural area. It is the ninth most populated county in the State of California.

Contra Costa's landmark is Mount Diablo, that sets a beautiful mountain backdrop, rising 3,849 feet at the northern end of the Diablo Range. Mt. Diablo State Park is one of several recreational areas that residents and visitors enjoy throughout the year. The East Bay Regional Park District is comprised of more than 100,000 acres within 65 parks, including more than 1,200 miles of trails.