USStateMap

Illinois County Map

Illinois has 102 counties. Cook County is the most populous, with 5,275,541 residents in 2020, and McLean County is the largest by land area at 1,183.2 sq mi. The capital, Springfield, is the seat of Sangamon County.

County map of Illinois showing all 102 counties

County lines are switched on when the interactive map loads, over an OpenStreetMap base map with major cities (capital in red). Hover over a county to see its name, or untick Show counties to hide the lines.

102counties
Cookmost populous: 5,275,541
McLeanlargest: 1,183.2 sq mi of land
Putnamsmallest: 160.1 sq mi of land

List of Illinois counties

CountyCounty seatPopulation (2020)Land area (sq mi)
Adams CountyQuincy65,737855.1
Alexander CountyCairo5,240235.4
Bond CountyGreenville16,725380.3
Boone CountyBelvidere53,448280.7
Brown CountyMount Sterling6,244305.7
Bureau CountyPrinceton33,244869.1
Calhoun CountyHardin4,437253.8
Carroll CountyMount Carroll15,702445.4
Cass CountyVirginia13,042375.8
Champaign CountyUrbana205,865996.1
Christian CountyTaylorville34,032709.5
Clark CountyMarshall15,455501.4
Clay CountyLouisville13,288468.4
Clinton CountyCarlyle36,899473.9
Coles CountyCharleston46,863508.3
Cook CountyChicago5,275,541944.9
Crawford CountyRobinson18,679443.6
Cumberland CountyToledo10,450345.9
De Witt CountyClinton15,516397.6
DeKalb CountySycamore100,420631.3
Douglas CountyTuscola19,740416.6
DuPage CountyWheaton932,877327.8
Edgar CountyParis16,866623.3
Edwards CountyAlbion6,245222.4
Effingham CountyEffingham34,668478.8
Fayette CountyVandalia21,488716.4
Ford CountyPaxton13,534485.6
Franklin CountyBenton37,804408.9
Fulton CountyLewistown33,609865.7
Gallatin CountyShawneetown4,946322.9
Greene CountyCarrollton11,985543.0
Grundy CountyMorris52,533418.1
Hamilton CountyMcLeansboro7,993434.6
Hancock CountyCarthage17,620793.7
Hardin CountyElizabethtown3,649177.4
Henderson CountyOquawka6,387378.8
Henry CountyCambridge49,284823.1
Iroquois CountyWatseka27,0771,117.4
Jackson CountyMurphysboro52,974583.6
Jasper CountyNewton9,287494.6
Jefferson CountyMount Vernon37,113571.2
Jersey CountyJerseyville21,512369.7
Jo Daviess CountyGalena22,035600.9
Johnson CountyVienna13,308343.7
Kane CountyGeneva516,522519.4
Kankakee CountyKankakee107,502676.5
Kendall CountyYorkville131,869320.2
Knox CountyGalesburg49,967716.4
LaSalle CountyOttawa109,6581,135.2
Lake CountyWaukegan714,342443.6
Lawrence CountyLawrenceville15,280372.2
Lee CountyDixon34,145724.8
Livingston CountyPontiac35,8151,043.6
Logan CountyLincoln27,987618.1
Macon CountyDecatur103,998580.6
Macoupin CountyCarlinville44,967863.0
Madison CountyEdwardsville265,859715.5
Marion CountySalem37,729572.5
Marshall CountyLacon11,742386.8
Mason CountyHavana13,086539.4
Massac CountyMetropolis14,169237.2
McDonough CountyMacomb27,238589.3
McHenry CountyWoodstock310,229603.4
McLean CountyBloomington170,9541,183.2
Menard CountyPetersburg12,297314.4
Mercer CountyAledo15,699561.2
Monroe CountyWaterloo34,962385.3
Montgomery CountyHillsboro28,288703.8
Morgan CountyJacksonville32,915568.9
Moultrie CountySullivan14,526336.0
Ogle CountyOregon51,788758.7
Peoria CountyPeoria181,830618.7
Perry CountyPinckneyville20,945441.9
Piatt CountyMonticello16,673439.2
Pike CountyPittsfield14,739831.4
Pope CountyGolconda3,763368.9
Pulaski CountyMound City5,193199.3
Putnam CountyHennepin5,637160.1
Randolph CountyChester30,163575.4
Richland CountyOlney15,813360.0
Rock Island CountyRock Island144,672427.5
Saline CountyHarrisburg23,768380.0
Sangamon CountySpringfield196,343868.3
Schuyler CountyRushville6,902437.3
Scott CountyWinchester4,949250.8
Shelby CountyShelbyville20,990758.5
St. Clair CountyBelleville257,400657.7
Stark CountyToulon5,400288.1
Stephenson CountyFreeport44,630564.2
Tazewell CountyPekin131,343646.5
Union CountyJonesboro17,244413.4
Vermilion CountyDanville74,188898.3
Wabash CountyMount Carmel11,361223.3
Warren CountyMonmouth16,835542.4
Washington CountyNashville13,761562.6
Wayne CountyFairfield16,179713.8
White CountyCarmi13,877495.0
Whiteside CountyMorrison55,691684.1
Will CountyJoliet696,355835.9
Williamson CountyMarion67,153420.2
Winnebago CountyRockford285,350513.0
Woodford CountyEureka38,467527.5

Click a column heading to sort. Land area excludes water.

Most populous counties

Illinois had 12,812,508 residents in the 2020 Census. The five most populous counties held 63.5 percent of them:

  1. Cook County (seat Chicago): 5,275,541, or 41.2 percent of the state
  2. DuPage County (seat Wheaton): 932,877, or 7.3 percent of the state
  3. Lake County (seat Waukegan): 714,342, or 5.6 percent of the state
  4. Will County (seat Joliet): 696,355, or 5.4 percent of the state
  5. Kane County (seat Geneva): 516,522, or 4.0 percent of the state

The least populous is Hardin County, with 3,649 residents. The median Illinois county had 27,077 people in 2020.

Largest and smallest counties

By land area, the largest Illinois counties are McLean County (1,183.2 sq mi), LaSalle County (1,135.2 sq mi) and Iroquois County (1,117.4 sq mi). The smallest are Putnam County (160.1 sq mi), Hardin County (177.4 sq mi) and Pulaski County (199.3 sq mi).

The average Illinois county covers 544.2 sq mi of land. McLean County is 7.4 times the land area of Putnam County.

How counties work in Illinois

Cook County, seat Chicago, is the second most populous county in the United States after Los Angeles County. Chicago lies almost entirely in Cook County; a small part of the city around O’Hare International Airport extends into DuPage County.

Most Illinois counties are divided into civil townships, which handle local services such as township roads and property assessment; the remaining counties have no townships and are run by a board of county commissioners.

The collar counties around Cook (DuPage, Kane, Lake, McHenry and Will) are the main suburban counties around Chicago. The state capital, Springfield, is the seat of Sangamon County in central Illinois.

Printable Illinois county maps

Download the labeled map with every county name, or the blank county map for quizzes and coloring; both are SVG files that print sharply at any size and are free for personal and classroom use.

Labeled county map of Illinois
Labeled SVGBlank SVGState outline PNG

Frequently asked questions

How many counties are in Illinois?

Illinois has 102 counties. Cook County has the most people and Hardin County the fewest.

What is the largest county in Illinois?

McLean County, with 1,183.2 sq mi of land. Its seat is Bloomington.

What is the most populous county in Illinois?

Cook County, with 5,275,541 residents in the 2020 Census, 41.2 percent of the state total.

What county is Chicago in?

Cook County, where Chicago is the county seat. A small part of the city near O’Hare International Airport is in DuPage County.

More Illinois and county maps

See the Illinois state map for cities, geography and highways.

County maps of neighboring states: Indiana · Iowa · Kentucky · Missouri · Wisconsin

Browse all 50 state maps.

Sources: U.S. Census Bureau (2020 Census, 2020 Gazetteer, boundaries); county seats from Wikipedia county lists cross-checked with Wikidata. Last reviewed October 2026.