60115 -- U.S. ZIP code Municipality (1990): DE KALB, Illinois All ZIPs for this municipality (1990): 60115 Population (2000): 42372 Housing Units (2000): 15101 Land area (2000): 87.507673 sq. miles (226.643824 sq. km) Water area (2000): 0.115984 sq. miles (0.300396 sq. km) Total area (2000): 87.623657 sq. miles (226.944220 sq. km) Located within: Illinois (IL) Location: 41.924127 N, 88.746179 W