Seneca, SD -- U.S. town in South Dakota Population (2000): 58 Housing Units (2000): 36 Land area (2000): 0.411362 sq. miles (1.065423 sq. km) Water area (2000): 0.000000 sq. miles (0.000000 sq. km) Total area (2000): 0.411362 sq. miles (1.065423 sq. km) FIPS code: 58180 Located within: South Dakota (SD), FIPS 46 Location: 45.060962 N, 99.509911 W ZIP Codes (1990): 57473 Note: some ZIP codes may be omitted esp. for suburbs. Headwords: Seneca, SD Seneca