Walnut, KS -- U.S. city in Kansas Population (2000): 221 Housing Units (2000): 116 Land area (2000): 0.990805 sq. miles (2.566174 sq. km) Water area (2000): 0.000000 sq. miles (0.000000 sq. km) Total area (2000): 0.990805 sq. miles (2.566174 sq. km) FIPS code: 74950 Located within: Kansas (KS), FIPS 20 Location: 37.600359 N, 95.075867 W ZIP Codes (1990): 66780 Note: some ZIP codes may be omitted esp. for suburbs. Headwords: Walnut, KS Walnut