Keystone, IA -- U.S. city in Iowa Population (2000): 687 Housing Units (2000): 281 Land area (2000): 0.370289 sq. miles (0.959043 sq. km) Water area (2000): 0.000000 sq. miles (0.000000 sq. km) Total area (2000): 0.370289 sq. miles (0.959043 sq. km) FIPS code: 41115 Located within: Iowa (IA), FIPS 19 Location: 42.000915 N, 92.198544 W ZIP Codes (1990): 52249 Note: some ZIP codes may be omitted esp. for suburbs. Headwords: Keystone, IA Keystone