| | Description: | Grundy County, located in northern Illinois, covers an area of 420 square miles and had a 2003 population of 39,528, according to estimates by the U.S. Department of Commerce's Bureau of the Census. Using these figures, Grundy County was the 69th largest county in Illinois geographically, but 35th largest in terms of population. Combining these two measures, Grundy County had the 26th highest population density per square mile among Illinois 102 counties. | |
