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 Headwords: Cook Cook, IL Cook County Cook County, IL