| Description: | LaSalle County, located in north central Illinois, covers an area of 1,135 square miles and had a 2003 population of 112,037, according to estimates by the U.S. Department of Commerce's Bureau of the Census. Using these figures, LaSalle County was the 101st largest county in Illinois geographically, but 16th largest in terms of population. Combining these two measures, LaSalle County had the 24th highest population density per square mile among Illinois 102 counties. | |