| Description: | Calhoun County, located in western Illinois, covers an area of 254 square miles and had a 2003 population of 5,069, according to estimates by the U.S. Department of Commerce's Bureau of the Census. Using these figures, Calhoun County was the 9th smallest county in Illinois geographically, but 3rd smallest in terms of population. Combining these two measures, Calhoun County had the 5th smallest population density per square mile among Illinois 102 counties. | |