| Description: | Cass County, located in western Illinois, covers an area of 376 square miles and had a 2003 population of 13,841, according to estimates by the U.S. Department of Commerce's Bureau of the Census. Using these figures, Cass County was the 23rd smallest county in Illinois geographically, but 20th largest in terms of population. Combining these two measures, Cass County had the 32nd highest population density per square mile among Illinois 102 counties. | |