5.09 M
Population
2nd in the U.S.
4,235 km²
Area
Chicago
County seat
≈ 21%
Foreign-born
Cook County
Cook County is the second-most populous county in the United States, home to Chicago and roughly two-fifths of all Illinois residents.
Cook County is the second-most populous county in the United States, home to Chicago and roughly two-fifths of all Illinois residents.