'Cook County, IL' definitions:

Cook -- U.S. County in Illinois

From: Gazetteer 2000
Name :
Cook -- U.S. County in Illinois
Population (2000) :
5376741
Housing Units (2000) :
2096121
Land area (2000) :
945.680365 sq. miles (2449.300798 sq. km)
Water area (2000) :
689.360841 sq. miles (1785.436307 sq. km)
Total area (2000) :
1635.041206 sq. miles (4234.737105 sq. km)
Located within :
Illinois (IL), FIPS 17
Location :
41.837649 N, 87.767817 W