Niwot, CO -- U.S. Census Designated Place in Colorado Population (2000): 4160 Housing Units (2000): 1546 Land area (2000): 4.053159 sq. miles (10.497632 sq. km) Water area (2000): 0.000000 sq. miles (0.000000 sq. km) Total area (2000): 4.053159 sq. miles (10.497632 sq. km) FIPS code: 53780 Located within: Colorado (CO), FIPS 08 Location: 40.099855 N, 105.160305 W ZIP Codes (1990): Note: some ZIP codes may be omitted esp. for suburbs. Headwords: Niwot, CO Niwot