Waterloo, WI -- U.S. city in Wisconsin Population (2000): 3259 Housing Units (2000): 1293 Land area (2000): 3.907351 sq. miles (10.119993 sq. km) Water area (2000): 0.024214 sq. miles (0.062715 sq. km) Total area (2000): 3.931565 sq. miles (10.182708 sq. km) FIPS code: 83925 Located within: Wisconsin (WI), FIPS 55 Location: 43.183660 N, 88.989965 W ZIP Codes (1990): 53594 Note: some ZIP codes may be omitted esp. for suburbs. Headwords: Waterloo, WI Waterloo