Pittsburg, CA -- U.S. city in California Population (2000): 56769 Housing Units (2000): 18300 Land area (2000): 15.600231 sq. miles (40.404412 sq. km) Water area (2000): 1.222101 sq. miles (3.165228 sq. km) Total area (2000): 16.822332 sq. miles (43.569640 sq. km) FIPS code: 57456 Located within: California (CA), FIPS 06 Location: 38.015021 N, 121.892491 W ZIP Codes (1990): Note: some ZIP codes may be omitted esp. for suburbs. Headwords: Pittsburg, CA Pittsburg