'Madison County, IL' definitions:
Madison -- U.S. County in Illinois
From: Gazetteer 2000
Name :
Madison -- U.S. County in Illinois
Population (2000) :
258941
Housing Units (2000) :
108942
Land area (2000) :
725.018183 sq. miles (1877.788394 sq. km)
Water area (2000) :
15.331733 sq. miles (39.709004 sq. km)
Total area (2000) :
740.349916 sq. miles (1917.497398 sq. km)
Located within :
Illinois (IL), FIPS 17
Location :
38.812515 N, 90.018837 W