Onalaska, WI -- U.S. city in Wisconsin Population (2000): 14839 Housing Units (2000): 6070 Land area (2000): 9.094918 sq. miles (23.555728 sq. km) Water area (2000): 0.581813 sq. miles (1.506888 sq. km) Total area (2000): 9.676731 sq. miles (25.062616 sq. km) FIPS code: 59925 Located within: Wisconsin (WI), FIPS 55 Location: 43.888266 N, 91.218624 W ZIP Codes (1990): 54650 Note: some ZIP codes may be omitted esp. for suburbs. Headwords: Onalaska, WI Onalaska