Explore Oakley local geography, civic resources and voter guides, with dated official population and registration facts for Contra Costa County.
At a glance: Oakley is an incorporated city in Contra Costa County. Population: 47,039 (California Department of Finance estimate as of January 1, 2026). Registered voters: 29,087 (California Secretary of State, as of September 4, 2026).
Oakley sits at the inland edge of the Delta, where residential neighborhoods, vineyards, and former agricultural land meet the San Joaquin River's tidal landscape. Big Break makes the city's relationship to the estuary especially visible. Big Break Regional Shoreline offers trails, shoreline access, and a visitor center interpreting the Delta. It is an East Bay Regional Park District facility, complementing rather than forming part of Oakley's municipal park system. Oakley incorporated on July 1, 1999, making it the newest incorporated city in Contra Costa County. It is a general-law city with council-manager government.
The East Bay Regional Park District operates Big Break, including its visitor center.
The official park address is 69 Big Break Road in Oakley.
Use Contra Costa County Elections for registration, ballots, and voting locations; consult the city for municipal candidate matters.
29,087 (California Secretary of State, as of September 4, 2026).
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