61530 -- U.S. ZIP code Municipality (1990): EUREKA, Illinois All ZIPs for this municipality (1990): 61530 Population (2000): 6181 Housing Units (2000): 2237 Land area (2000): 53.563499 sq. miles (138.728820 sq. km) Water area (2000): 0.060989 sq. miles (0.157960 sq. km) Total area (2000): 53.624488 sq. miles (138.886780 sq. km) Located within: Illinois (IL) Location: 40.718228 N, 89.271539 W