| Description: | Stephenson County, located in northern Illinois, covers an area of 564 square miles and had a 2003 population of 48,151, according to estimates by the U.S. Department of Commerce's Bureau of the Census. Using these figures, Stephenson County was the 43rd largest county in Illinois geographically, but 31st largest in terms of population. Combining these two measures, Stephenson County had the 29th highest population density per square mile among Illinois 102 counties. | |