Johnstown, CO -- U.S. town in Colorado Population (2000): 3827 Housing Units (2000): 1371 Land area (2000): 1.143761 sq. miles (2.962326 sq. km) Water area (2000): 0.000000 sq. miles (0.000000 sq. km) Total area (2000): 1.143761 sq. miles (2.962326 sq. km) FIPS code: 39855 Located within: Colorado (CO), FIPS 08 Location: 40.336240 N, 104.920279 W ZIP Codes (1990): 80534 Note: some ZIP codes may be omitted esp. for suburbs. Headwords: Johnstown, CO Johnstown