Contra Costa County is home to more than one million residents, and was one of the original 27 counties established in California in 1850. Comprised of 19 cities and many established communities in the unincorporated area, it is the ninth most populous county in the state.
The most notable landmark in the county is Mount Diablo, rising 3,849 feet at the northern end of the Diablo Range. It is the centerpiece of Mt. Diablo State Park, one of many recreation areas residents and visitors can enjoy. 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.