Walnut, IA -- U.S. city in Iowa Population (2000): 778 Housing Units (2000): 350 Land area (2000): 2.144188 sq. miles (5.553422 sq. km) Water area (2000): 0.000000 sq. miles (0.000000 sq. km) Total area (2000): 2.144188 sq. miles (5.553422 sq. km) FIPS code: 82065 Located within: Iowa (IA), FIPS 19 Location: 41.480999 N, 95.221116 W ZIP Codes (1990): 51577 Note: some ZIP codes may be omitted esp. for suburbs. Headwords: Walnut, IA Walnut