| Description: | McDonough County, located in western Illinois, covers an area of 589 square miles and had a 2003 population of 32,852, according to estimates by the U.S. Department of Commerce's Bureau of the Census. Using these figures, McDonough County was the 36th largest county in Illinois geographically, but 47th largest in terms of population. Combining these two measures, McDonough County had the 47th highest population density per square mile among Illinois 102 counties. | |