STATE ยท IL

Counties in Illinois

Illinois has 102 counties and county equivalents. The most populous is Cook County with 5,087,072 people (Census 2023 estimate).

CountyTypeFIPSPopulation (2023)
Adams Countycounty1700164,441
Alexander Countycounty170034,695
Bond Countycounty1700516,450
Boone Countycounty1700753,202
Brown Countycounty170096,294
Bureau Countycounty1701132,729
Calhoun Countycounty170134,317
Carroll Countycounty1701515,526
Cass Countycounty1701712,596
Champaign Countycounty17019205,644
Christian Countycounty1702133,228
Clark Countycounty1702315,088
Clay Countycounty1702512,999
Clinton Countycounty1702736,785
Coles Countycounty1702946,060
Cook Countycounty170315,087,072
Crawford Countycounty1703318,300
Cumberland Countycounty1703510,261
DeKalb Countycounty17037100,288
De Witt Countycounty1703915,365
Douglas Countycounty1704119,629
DuPage Countycounty17043921,213
Edgar Countycounty1704516,334
Edwards Countycounty170475,968
Effingham Countycounty1704934,331
Fayette Countycounty1705121,164
Ford Countycounty1705313,250
Franklin Countycounty1705537,138
Fulton Countycounty1705732,541
Gallatin Countycounty170594,670
Greene Countycounty1706111,543
Grundy Countycounty1706353,578
Hamilton Countycounty170657,911
Hancock Countycounty1706717,186
Hardin Countycounty170693,569
Henderson Countycounty170716,088
Henry Countycounty1707348,448
Iroquois Countycounty1707526,136
Jackson Countycounty1707752,141
Jasper Countycounty170799,144
Jefferson Countycounty1708136,320
Jersey Countycounty1708321,091
Jo Daviess Countycounty1708521,756
Johnson Countycounty1708713,326
Kane Countycounty17089514,982
Kankakee Countycounty17091105,940
Kendall Countycounty17093139,976
Knox Countycounty1709548,411
Lake Countycounty17097708,760
LaSalle Countycounty17099108,309
Lawrence Countycounty1710114,813
Lee Countycounty1710333,654
Livingston Countycounty1710535,320
Logan Countycounty1710727,590
McDonough Countycounty1710926,839
McHenry Countycounty17111312,800
McLean Countycounty17113170,441
Macon Countycounty17115100,591
Macoupin Countycounty1711744,018
Madison Countycounty17119262,752
Marion Countycounty1712136,673
Marshall Countycounty1712311,683
Mason Countycounty1712512,523
Massac Countycounty1712713,661
Menard Countycounty1712911,954
Mercer Countycounty1713115,487
Monroe Countycounty1713334,957
Montgomery Countycounty1713527,663
Morgan Countycounty1713732,140
Moultrie Countycounty1713914,342
Ogle Countycounty1714151,265
Peoria Countycounty17143177,513
Perry Countycounty1714520,503
Piatt Countycounty1714716,714
Pike Countycounty1714914,342
Pope Countycounty171513,707
Pulaski Countycounty171534,911
Putnam Countycounty171555,561
Randolph Countycounty1715729,815
Richland Countycounty1715915,488
Rock Island Countycounty17161141,236
St. Clair Countycounty17163251,018
Saline Countycounty1716522,873
Sangamon Countycounty17167193,491
Schuyler Countycounty171696,733
Scott Countycounty171714,710
Shelby Countycounty1717320,568
Stark Countycounty171755,218
Stephenson Countycounty1717743,105
Tazewell Countycounty17179129,541
Union Countycounty1718116,667
Vermilion Countycounty1718371,652
Wabash Countycounty1718510,942
Warren Countycounty1718716,185
Washington Countycounty1718913,536
Wayne Countycounty1719115,761
White Countycounty1719313,401
Whiteside Countycounty1719554,498
Will Countycounty17197700,728
Williamson Countycounty1719966,706
Winnebago Countycounty17201280,922
Woodford Countycounty1720338,285

Sources: U.S. Census Bureau geographic reference files; Census Bureau Population Estimates, Vintage 2023. Last reviewed 2026-10-27. Looking for yours? Find your county.