Illinois Census Data

Data for Illinois show that the five most populous incorporated places and their 2010 Census counts are Chicago, 2,695,598; Aurora, 197,899; Rockford, 152,871; Joliet, 147,433; and Naperville, 141,853. Chicago decreased by 6.9 percent since the 2000 Census. Aurora grew by 38.4 percent, Rockford grew by 1.8 percent, Joliet grew by 38.8 percent, and Naperville grew by 10.5 percent.

The largest county is Cook with a population of 5,194,675. Its population decreased by 3.4 percent since 2000. The other counties in the top five include DuPage, with a population of 916,924 (increase of 1.4 percent); Lake, 703,462 (increase of 9.2 percent); Will, 677,560 (increase of 34.9 percent); and Kane, 515,269 (increase of 27.5 percent). Read More »