| Description: | McLean County, located in central Illinois, covers an area of 1,183 square miles and had a 2003 population of 156,879, according to estimates by the U.S. Department of Commerce's Bureau of the Census. Using these figures, McLean County was the largest county in Illinois geographically, but 13th largest in terms of population. Combining these two measures, McLean County had the 21st highest population density per square mile among Illinois 102 counties. | |