'Mason County, IL' definitions:
Mason -- U.S. County in Illinois
From: Gazetteer 2000
Name :
Mason -- U.S. County in Illinois
Population (2000) :
16038
Housing Units (2000) :
7033
Land area (2000) :
538.942504 sq. miles (1395.854617 sq. km)
Water area (2000) :
24.426097 sq. miles (63.263298 sq. km)
Total area (2000) :
563.368601 sq. miles (1459.117915 sq. km)
Located within :
Illinois (IL), FIPS 17
Location :
40.260702 N, 89.913299 W