Red Oak, IA -- U.S. city in Iowa Population (2000): 6197 Housing Units (2000): 2985 Land area (2000): 3.678384 sq. miles (9.526970 sq. km) Water area (2000): 0.056830 sq. miles (0.147189 sq. km) Total area (2000): 3.735214 sq. miles (9.674159 sq. km) FIPS code: 66135 Located within: Iowa (IA), FIPS 19 Location: 41.011681 N, 95.227227 W ZIP Codes (1990): 51566 Note: some ZIP codes may be omitted esp. for suburbs. Headwords: Red Oak, IA Red Oak