61261 -- U.S. ZIP code Municipality (1990): LYNDON, Illinois All ZIPs for this municipality (1990): 61261 Population (2000): 963 Housing Units (2000): 407 Land area (2000): 18.622112 sq. miles (48.231046 sq. km) Water area (2000): 0.062043 sq. miles (0.160690 sq. km) Total area (2000): 18.684155 sq. miles (48.391736 sq. km) Located within: Illinois (IL) Location: 41.719782 N, 89.921162 W