'Williamson County, IL' definitions:

Williamson -- U.S. County in Illinois

From: Gazetteer 2000
Name :
Williamson -- U.S. County in Illinois
Population (2000) :
61296
Housing Units (2000) :
27703
Land area (2000) :
423.413908 sq. miles (1096.636941 sq. km)
Water area (2000) :
20.962111 sq. miles (54.291615 sq. km)
Total area (2000) :
444.376019 sq. miles (1150.928556 sq. km)
Located within :
Illinois (IL), FIPS 17
Location :
37.749230 N, 88.972314 W