IL History & Facts
County Information - Illinois
By Cynthia Kirkeby
May 22, 2006, 13:31 PST

County Information for Illinois


There are 102 counties in the state of Illinois.

The largest Illinois county by size is McLean County, which is 1,184 square miles.

The largest Illinois county by population is Cook County, which has a population of 5,376,741 .

Source: National Association of Counties


Here are Illinois QuickFacts from the U.S. Census Bureau.