Contra Costa County is a county located in the U.S. state of California, in the East Bay of the San Francisco Bay Area. As of the 2020 United States Census, the population was 1,165,927. The county seat is Martinez. It occupies the northern portion of the East Bay region of the San Francisco Bay Area and is primarily suburban. The county's name refers to its position on the other side of the bay from San Francisco. Contra Costa County is included in the San Francisco–Oakland–Berkeley, CA Metropolitan Statistical Area.
Antioch is the third-most populous city in Contra Costa County, California, United States. The city is located in the East Bay region of the San Francisco Bay Area along the Sacramento–San Joaquin River Delta. The city's population was 115,291 at the 2020 census. The city has grown substantially more diverse since the 1970s.
Brentwood is a city in Contra Costa County, California, United States. It is located in the East Bay region of the San Francisco Bay Area. The population is 66,854 as of 2022, an increase of 287% from 23,302 at the 2000 census.
Byron is a census designated place (CDP) in Contra Costa County, California, United States.
Discovery Bay is a census-designated place (CDP) in eastern Contra Costa County, California in the United States, about 60 miles (97 km) from San Francisco. It is located in the San Francisco Bay Area. As of 2020, its population was 15,358, a 15% percent gain from 13,352 at the 2010 census.
Knightsen is a census-designated place (CDP) in Contra Costa County, California, in the United States. As of the 2010 census, the CDP population was 1,568, up from 861 reported in the 2000 census.
Oakley is a city in Contra Costa County, California, United States. It is within the nine-county San Francisco Bay Area. The population at the 2020 United States census was 43,357. Oakley was incorporated in 1999, making it the newest incorporated city in Contra Costa County.
California's 9th congressional district is a congressional district in the U.S. state of California. Josh Harder, a Democrat, has represented the district since January 2023.
California's 10th congressional district is a congressional district in the U.S. state of California. Currently, the 10th district encompasses parts of the eastern San Francisco Bay Area. It is currently represented by Democrat Mark DeSaulnier.
Tri Delta Transit, formally the Eastern Contra Costa Transit Authority, is a joint powers agency of the governments of Pittsburg, Antioch, Oakley, Brentwood, and Contra Costa County that provides bus service for the eastern area of Contra Costa County, California, United States. Tri Delta Transit local buses connect to the BART rapid transit system at Antioch, Pittsburg Center, Pittsburg/Bay Point and Concord. Tri Delta Transit buses also connect with County Connection bus service. In 2023, the system had a ridership of 1,304,700, or about 4,700 per weekday as of the third quarter of 2024.
The John Swett Unified School District (JSUSD) is a public school district in Contra Costa County, California. It currently operates one elementary school, one middle school, and one standard high school and another for Continuing and Alternative education. The current district superintendent is Charles Miller.
The Contra Costa County Board of Supervisors is the governing body for Contra Costa County, California, in the San Francisco Bay Area's East Bay region. Members of the Board of supervisors are elected from districts, based on their residence.
Rancho Los Méganos was a 13,316-acre (53.89 km2) Mexican land grant in the southwestern Sacramento-San Joaquin Delta region of present-day Contra Costa County, California.
Bethel Island is an island in the Sacramento–San Joaquin River Delta of Contra Costa County, California, approximately 10 kilometres (6.2 mi) east of Antioch. The island describes itself as "the heart of the California Delta."
Marsh Creek is a stream in east Contra Costa County, California in Northern California which rises on the eastern side of Mount Diablo and flows 30 miles (48 km) to the Sacramento–San Joaquin River Delta at Oakley, California, near Big Break Regional Shoreline. The creek flows through Marsh Creek State Park (California), where water is impounded to form Marsh Creek Reservoir, then through the city of Brentwood, California.
eBART is a hybrid rail branch line of the Bay Area Rapid Transit (BART) system in eastern Contra Costa County, California, United States. The line extends the Yellow Line beyond Pittsburg/Bay Point station to Antioch station.
Brentwood Union School District is a public school district based in Contra Costa County, California.
Oakley Union Elementary School District is a public school district in Contra Costa County, California, United States.
East Contra Costa Fire Protection District (ECCFPD) is an agency that is responsible for providing fire protection in the most eastern section of Contra Costa. The district was created on September 12, 2002, by the Bethel Island, East Diablo, and Oakley Fire Protection Districts. The district currently has three fire stations with three fire fighters each. Its territory covers 247 square miles and includes two cities, plus much of the county's unincorporated area. The incorporated cities are: Antioch, Brentwood, and Oakley. Unincorporated community areas are Bethel Island, Discovery Bay, Byron, Knightsen and Marsh Creek/Morgan Territory. As of 2020, the district claims that it serves a population of 128,000. Financial support is primarily from property taxes collected by the county.
Contra Costa is the 150th American Viticultural Area (AVA) in California located in the San Francisco Bay Area. It lies east of San Pablo Bay in Contra Costa County on the southern banks of the Carquinez Strait encompassing the area around the cities of Concord, Martinez, Pittsburg, Antioch and Brentwood. It was established on March 15, 2024 by the Alcohol and Tobacco Tax and Trade Bureau (TTB), Treasury after reviewing the petition submitted by Patrick Shabram on behalf of the Contra Costa Winegrowers Association proposing to establish an viticultural area named "Contra Costa."
