'Cass County, IL' definitions:

Cass -- U.S. County in Illinois

From: Gazetteer 2000
Name :
Cass -- U.S. County in Illinois
Population (2000) :
13695
Housing Units (2000) :
5784
Land area (2000) :
375.900754 sq. miles (973.578443 sq. km)
Water area (2000) :
7.830552 sq. miles (20.281035 sq. km)
Total area (2000) :
383.731306 sq. miles (993.859478 sq. km)
Located within :
Illinois (IL), FIPS 17
Location :
39.975926 N, 90.269918 W