Macomb, IL -- U.S. city in Illinois Population (2000): 18558 Housing Units (2000): 7037 Land area (2000): 9.849193 sq. miles (25.509291 sq. km) Water area (2000): 0.401447 sq. miles (1.039743 sq. km) Total area (2000): 10.250640 sq. miles (26.549034 sq. km) FIPS code: 45889 Located within: Illinois (IL), FIPS 17 Location: 40.460501 N, 90.674048 W ZIP Codes (1990): 61455 Note: some ZIP codes may be omitted esp. for suburbs. Headwords: Macomb, IL Macomb