61442 -- U.S. ZIP code Municipality (1990): KEITHSBURG, Illinois All ZIPs for this municipality (1990): 61442 Population (2000): 920 Housing Units (2000): 437 Land area (2000): 26.616109 sq. miles (68.935403 sq. km) Water area (2000): 0.037530 sq. miles (0.097202 sq. km) Total area (2000): 26.653639 sq. miles (69.032605 sq. km) Located within: Illinois (IL) Location: 41.092081 N, 90.927436 W