| Description: | Henry County, located in northwestern Illinois, covers an area of 823 square miles and had a 2003 population of 50,644, according to estimates by the U.S. Department of Commerce's Bureau of the Census. Using these figures, Henry County was the 15th largest county in Illinois geographically, but 29th largest in terms of population. Combining these two measures, Henry County had the 42nd highest population density per square mile among Illinois 102 counties. | |