| Description: | Washington County, located in southern Illinois, covers an area of 563 square miles and had a 2003 population of 15,179, according to estimates by the U.S. Department of Commerce's Bureau of the Census. Using these figures, Washington County was the 44th largest county in Illinois geographically, but 75th largest in terms of population. Combining these two measures, Washington County had the 14th lowest population density per square mile among Illinois 102 counties. | |