The county has a strong economy, with major industries including healthcare, education, and technology. Some of the largest employers in Contra Costa County include Kaiser Permanente, Chevron, and the Mount Diablo Unified School District.
2026 REQUEST FOR VALUE REVIEW (PROP 8) California State Revenue and Taxation Code, Section 51 authorizes the Assessor to temporarily lower the assessed value of any real property when it is greater than the market value as of January 1, lien date.
Contra Costa County, California Contra Costa County County seat Martinez Largest city Concord (population and land area) Richmond (total area) Government • Type Council–CAO33 more rows
Nortonville, California. Nortonville is an unincorporated ghost town in Contra Costa County, California. It was located on Kirker Creek 5.5 miles (9 km) north-northeast of Mount Diablo, at an elevation of 801 feet (244 m).
County seat, Martinez. Created February 18, 1850. The name signifies “opposite coast,” because of its situation opposite San Francisco, in an easterly direction, on San Francisco Bay.
East Contra Costa County remains an economically diverse agricultural hub, supplying grocers and farmers markets and hosting the popular U-Pick season. Sweet corn, tomatoes, grapes, and dozens of other crops, including cannabis (approved by voters in 2016), grow in fertile soils and a moderate climate.
For code violations regarding issues in the public way, please contact the Department of Public Works or call 311.
Congressman Mark DeSaulnier (DE-SOWN-YAY) proudly represents California's 10th Congressional District, which includes much of Contra Costa County and a part of Alameda County.
The Superior Court of Contra Costa implemented its E-filing system in 2022. They selected Odyssey Case Manager from Tyler Technologies, a software solution in use by 29 of the 58 courts in the state.
How often do REAC inspections occur? Type of housingInspection frequency Public housing, multifamily housing, HUD-assisted nursing homes and assisted living facilities Inspected every 1 to 3 years. Properties that score well are inspected less often. Housing choice vouchers Before you move in. Then, every 1 to 2 years.