Antioch, CA -- U.S. city in California Population (2000): 90532 Housing Units (2000): 30116 Land area (2000): 26.948185 sq. miles (69.795477 sq. km) Water area (2000): 0.631797 sq. miles (1.636347 sq. km) Total area (2000): 27.579982 sq. miles (71.431824 sq. km) FIPS code: 02252 Located within: California (CA), FIPS 06 Location: 37.992421 N, 121.802225 W ZIP Codes (1990): 94509 Note: some ZIP codes may be omitted esp. for suburbs. Headwords: Antioch, CA Antioch