Thornton, IA -- U.S. city in Iowa Population (2000): 422 Housing Units (2000): 193 Land area (2000): 1.246453 sq. miles (3.228298 sq. km) Water area (2000): 0.000000 sq. miles (0.000000 sq. km) Total area (2000): 1.246453 sq. miles (3.228298 sq. km) FIPS code: 77880 Located within: Iowa (IA), FIPS 19 Location: 42.944972 N, 93.384115 W ZIP Codes (1990): 50479 Note: some ZIP codes may be omitted esp. for suburbs. Headwords: Thornton, IA Thornton