Contra Costa County is a county in the state of California. It is in the United States. As of the 2020 census, the population was 1,165,927.[1] The county seat is Martinez.[2] It is in the eastern part of the San Francisco Bay Area region.
- ↑ "QuickFacts: Contra Costa County, California". U.S. Census Bureau. Retrieved May 10, 2023.
- ↑ "Find a County". National Association of Counties. Archived from the original on May 31, 2011. Retrieved 2011-06-07.