First-level division
🇺🇸 Illinois
Subdivisions
Cook
Population 5,194,675
DuPage County
Population 916,924
Lake
Population 714,342
Will
Population 677,560
Kane
Population 532,403
McHenry
Population 308,760
Winnebago
Population 295,266
Madison
Population 269,282
Saint Clair
Population 257,400
Champaign
Population 201,081
Sangamon
Population 194,672
Peoria
Population 179,179
McLean
Population 169,572
Rock Island
Population 147,546
Tazewell
Population 131,803
Kendall
Population 114,736
LaSalle County
Population 113,924
Kankakee
Population 113,449
Macon
Population 110,768
DeKalb County
Population 105,160
Vermilion
Population 81,625
Williamson
Population 66,357
Adams
Population 65,737
Jackson
Population 60,218
Whiteside
Population 55,626
Boone
Population 53,544
Ogle
Population 53,497
Knox
Population 52,919
Henry
Population 50,486
Grundy
Population 50,063
Coles
Population 46,863
Macoupin
Population 45,313
Stephenson
Population 44,753
Franklin
Population 39,561
Marion
Population 39,437
Livingston
Population 38,950
Jefferson
Population 38,827
Woodford
Population 38,463
Clinton
Population 37,762
Fulton
Population 37,069
Lee
Population 36,031
Morgan
Population 35,547
Bureau
Population 34,978
Christian
Population 34,800
Effingham
Population 34,242
Randolph
Population 33,476
Monroe
Population 32,957
Logan
Population 30,305
Montgomery
Population 30,104
Iroquois
Population 27,604
McDonough
Population 27,238
Saline
Population 23,768
Jo Daviess
Population 22,678
Fayette
Population 22,140
Jersey
Population 21,512
Perry
Population 21,174
Shelby
Population 20,990
Douglas
Population 19,740
Hancock
Population 19,104
Crawford
Population 18,807
Union
Population 17,808
Warren
Population 17,707
Edgar
Population 16,866
Lawrence
Population 16,833
Wayne
Population 16,760
Bond
Population 16,725
Piatt
Population 16,673
DeWitt County
Population 16,561
Mercer
Population 16,434
Richland
Population 15,763
Pike
Population 15,611
Clark
Population 15,441
Massac
Population 15,429
Washington
Population 14,716
Moultrie
Population 14,526
Carroll
Population 14,305
White
Population 13,665
Cass
Population 13,642
Mason
Population 13,565
Ford
Population 13,264
Clay
Population 13,184
Greene
Population 13,044
Menard
Population 12,705
Marshall
Population 12,640
Johnson
Population 12,582
Wabash
Population 11,947
Cumberland
Population 11,048
Jasper
Population 9,698
Hamilton
Population 8,457
Alexander
Population 8,238
Henderson
Population 7,331
Schuyler
Population 6,907
Edwards
Population 6,721
Brown
Population 6,578
Pulaski
Population 6,161
Putnam
Population 6,006
Stark
Population 5,427
Scott
Population 5,355
Calhoun
Population 5,089
Gallatin
Population 5,058