County Maps US

Illinois County Map

Illinois has 102 counties. Together they cover 55,514 sq mi of land and 12,719,141 people.

Neighbouring areas are given different colours so their shared borders read clearly. These colours carry no data.

Boundaries from the 2025 Census cartographic boundary file, generalised so that no point moves by more than half a pixel at this width. Select any area to open its page.
Counties
102
7th most of the 51 states and DC
Population
12,719,141
6th largest
Land area
55,514
square miles
Density
229.1
people per square mile, computed

Sources: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026; US Census Bureau, Gazetteer Files, 2025 Gazetteer Files, released 10 September 2025. Retrieved 30 August 2026.

Download this map

Free to use and redistribute. The boundaries are public-domain Census Bureau data; attribution to County Maps US is appreciated but not required.

Satellite view

Aerial imagery of Illinois with the state boundary drawn on top. County lines are not drawn here: at this scale they would bury the picture, and the map above already carries them.

Aerial view of Illinois from the USGS National Map, with its boundary outlined
Imagery: USGS National Map, USGS Imagery Only, public domain, requested from USGS by your browser when you reach this point on the page, at 484 by 800 pixels. The boundary is the 2025 Census cartographic boundary file, reprojected to Web Mercator to match the imagery. You can also open the USGS National Map viewer.

The extremes of Illinois

Most populous

Cook County

5,194,625

Least populous

Hardin County

3,588

Largest by land area

McLean County

1,183 sq mi

Smallest by land area

Putnam County

160.1 sq mi

Most densely populated

Cook County

5,497 per sq mi

Highest median household income

DuPage County

$112,096

Which is the largest county in Illinois? The answer depends on whether you mean area or population.

The counties, by shape

Every one, drawn to its own scale so the small ones stay recognisable. Shape alone is not a size comparison; the table below carries the areas.

What the map does not say

The counties of Illinois are nowhere near the same size. McLean County covers 1,183 sq mi of land, 7.4 times the 160.1 sq mi of Putnam County. People are spread even less evenly: Cook County packs 5,497 per sq mi while Pope County holds 10.0 per sq mi.

They were not drawn in one sitting either. St. Clair County dates to 1790, and the boundaries were still being redrawn when Ford County was organised in 1859, 69 years later. Founding years come from Wikidata and are worth checking against the county's own history before citing.

Water is part of the picture too: 67.6% of Lake County is water, the most in the state, which is why its land area and total area disagree. And 80 of the 102 counties here share their names with counties in other states, so searching by name alone can land in the wrong place; the A to Z index lists every duplicate.

All 102 counties of Illinois

Sortable on any column. This table doubles as the text alternative to the map above: every area is a link, in alphabetical order, whether or not the map renders.

The 102 counties of Illinois, with population, land area, density, median household income, county seat and FIPS code.
NamePopulationLand areaDensityMedian incomeSeatFIPS
Adams County64,267855.2 sq mi75.2 per sq mi$66,220Quincy17001
Alexander County4,570235.4 sq mi19.4 per sq mi$47,043Cairo17003
Bond County16,959380.3 sq mi44.6 per sq mi$65,959Greenville17005
Boone County53,568280.7 sq mi191 per sq mi$84,571Belvidere17007
Brown County6,401305.7 sq mi20.9 per sq mi$67,917Mount Sterling17009
Bureau County32,510869.1 sq mi37.4 per sq mi$69,257Princeton17011
Calhoun County4,300253.8 sq mi16.9 per sq mi$93,203Hardin17013
Carroll County15,419445.4 sq mi34.6 per sq mi$60,758Mount Carroll17015
Cass County12,463375.8 sq mi33.2 per sq mi$68,125Virginia17017
Champaign County209,972996.1 sq mi211 per sq mi$63,683Urbana17019
Christian County33,443709.5 sq mi47.1 per sq mi$62,611Taylorville17021
Clark County15,114501.4 sq mi30.1 per sq mi$72,927Marshall17023
Clay County12,793468.4 sq mi27.3 per sq mi$60,417Louisville17025
Clinton County37,128473.9 sq mi78.3 per sq mi$86,588Carlyle17027
Coles County46,607508.3 sq mi91.7 per sq mi$56,478Charleston17029
Cook County5,194,625944.9 sq mi5,497 per sq mi$83,498Chicago17031
Crawford County18,648443.6 sq mi42.0 per sq mi$71,674Robinson17033
Cumberland County10,208345.9 sq mi29.5 per sq mi$73,327Toledo17035
De Witt County15,118397.6 sq mi38.0 per sq mi$71,678Clinton17039
DeKalb County101,835631.3 sq mi161 per sq mi$70,724Sycamore17037
Douglas County19,880416.7 sq mi47.7 per sq mi$77,320Tuscola17041
DuPage County934,298327.9 sq mi2,849 per sq mi$112,096Wheaton17043
Edgar County16,323623.3 sq mi26.2 per sq mi$59,941Paris17045
Edwards County5,898222.4 sq mi26.5 per sq mi$60,519Albion17047
Effingham County34,519478.8 sq mi72.1 per sq mi$80,404Effingham17049
Fayette County20,790716.5 sq mi29.0 per sq mi$60,944Vandalia17051
Ford County13,216485.6 sq mi27.2 per sq mi$62,439Paxton17053
Franklin County36,916408.9 sq mi90.3 per sq mi$56,740Benton, Illinois17055
Fulton County32,901865.7 sq mi38.0 per sq mi$60,599Lewistown17057
Gallatin County4,616322.9 sq mi14.3 per sq mi$59,219Shawneetown17059
Greene County11,313543.1 sq mi20.8 per sq mi$62,192Carrollton17061
Grundy County54,052418.1 sq mi129 per sq mi$92,235Morris17063
Hamilton County7,859434.7 sq mi18.1 per sq mi$65,746McLeansboro17065
Hancock County16,803793.7 sq mi21.2 per sq mi$65,865Carthage17067
Hardin County3,588177.4 sq mi20.2 per sq mi$54,271Elizabethtown17069
Henderson County5,984378.8 sq mi15.8 per sq mi$62,227Oquawka17071
Henry County48,095823.2 sq mi58.4 per sq mi$71,911Cambridge17073
Iroquois County26,1501,117 sq mi23.4 per sq mi$66,255Watseka17075
Jackson County52,501583.6 sq mi90.0 per sq mi$48,763Murphysboro17077
Jasper County9,032494.6 sq mi18.3 per sq mi$74,755Newton17079
Jefferson County36,147571.2 sq mi63.3 per sq mi$63,118Mount Vernon17081
Jersey County21,160369.6 sq mi57.3 per sq mi$80,361Jerseyville17083
Jo Daviess County21,594600.9 sq mi35.9 per sq mi$73,993Galena17085
Johnson County13,363343.7 sq mi38.9 per sq mi$62,528Vienna17087
Kane County525,757519.4 sq mi1,012 per sq mi$103,163Geneva17089
Kankakee County105,525676.5 sq mi156 per sq mi$71,281Kankakee17091
Kendall County145,470320.2 sq mi454 per sq mi$111,601Yorkville17093
Knox County47,767716.4 sq mi66.7 per sq mi$57,030Galesburg17095
Lake County719,339443.7 sq mi1,621 per sq mi$110,416Waukegan17097
LaSalle County107,7731,135 sq mi94.9 per sq mi$73,045Ottawa17099
Lawrence County13,790372.2 sq mi37.1 per sq mi$55,324Lawrenceville17101
Lee County32,914724.8 sq mi45.4 per sq mi$70,292Dixon17103
Livingston County35,0571,044 sq mi33.6 per sq mi$73,790Pontiac17105
Logan County27,182618.1 sq mi44.0 per sq mi$66,358Lincoln17107
Macon County99,300580.5 sq mi171 per sq mi$62,666Decatur17115
Macoupin County43,748863 sq mi50.7 per sq mi$70,805Carlinville17117
Madison County263,110715.5 sq mi368 per sq mi$75,793Edwardsville17119
Marion County36,382572.5 sq mi63.5 per sq mi$61,240Salem17121
Marshall County11,473386.8 sq mi29.7 per sq mi$71,585Lacon17123
Mason County12,411539.4 sq mi23.0 per sq mi$62,845Havana17125
Massac County13,502237.2 sq mi56.9 per sq mi$65,116Metropolis17127
McDonough County25,916589.3 sq mi44.0 per sq mi$52,795Macomb17109
McHenry County317,751603.4 sq mi527 per sq mi$104,802Woodstock17111
McLean County171,4191,183 sq mi145 per sq mi$79,905Bloomington17113
Menard County11,863314.4 sq mi37.7 per sq mi$82,176Petersburg17129
Mercer County15,229561.2 sq mi27.1 per sq mi$74,182Aledo17131
Monroe County34,840385.3 sq mi90.4 per sq mi$102,880Waterloo17133
Montgomery County28,076703.8 sq mi39.9 per sq mi$63,620Hillsboro17135
Morgan County32,515569 sq mi57.1 per sq mi$66,306Jacksonville17137
Moultrie County14,371336 sq mi42.8 per sq mi$71,784Sullivan17139
Ogle County51,399758.7 sq mi67.8 per sq mi$82,132Oregon17141
Peoria County178,553618.7 sq mi289 per sq mi$65,108Peoria17143
Perry County20,160441.9 sq mi45.6 per sq mi$62,118Pinckneyville17145
Piatt County16,791439.2 sq mi38.2 per sq mi$94,811Monticello17147
Pike County14,231831.4 sq mi17.1 per sq mi$59,777Pittsfield17149
Pope County3,672368.9 sq mi10.0 per sq mi$60,050Golconda17151
Pulaski County4,820199.3 sq mi24.2 per sq mi$42,463Mound City17153
Putnam County5,619160.1 sq mi35.1 per sq mi$75,590Hennepin17155
Randolph County29,921575.4 sq mi52.0 per sq mi$68,131Chester17157
Richland County15,219360 sq mi42.3 per sq mi$62,455Olney17159
Rock Island County141,869427.5 sq mi332 per sq mi$67,159Rock Island17161
Saline County22,772380 sq mi59.9 per sq mi$53,117Harrisburg17165
Sangamon County194,170868.2 sq mi224 per sq mi$75,357Springfield17167
Schuyler County6,657437.3 sq mi15.2 per sq mi$65,948Rushville17169
Scott County4,866250.8 sq mi19.4 per sq mi$66,705Winchester17171
Shelby County20,576758.5 sq mi27.1 per sq mi$72,095Shelbyville17173
St. Clair County250,708657.7 sq mi381 per sq mi$73,854Belleville17163
Stark County5,319288.1 sq mi18.5 per sq mi$62,878Toulon17175
Stephenson County43,220564.2 sq mi76.6 per sq mi$64,043Freeport17177
Tazewell County130,049646.5 sq mi201 per sq mi$77,982Pekin17179
Union County16,656413.4 sq mi40.3 per sq mi$55,728Jonesboro17181
Vermilion County71,259898.3 sq mi79.3 per sq mi$56,877Danville17183
Wabash County10,907223.3 sq mi48.8 per sq mi$57,086Mount Carmel17185
Warren County16,222542.4 sq mi29.9 per sq mi$67,385Monmouth17187
Washington County13,564562.6 sq mi24.1 per sq mi$78,224Nashville17189
Wayne County15,882713.8 sq mi22.2 per sq mi$55,521Fairfield17191
White County13,250495 sq mi26.8 per sq mi$54,813Carmi17193
Whiteside County54,121684.1 sq mi79.1 per sq mi$67,500Morrison17195
Will County712,253835.9 sq mi852 per sq mi$109,984Joliet17197
Williamson County67,225420.2 sq mi160 per sq mi$65,604Marion17199
Winnebago County283,674513 sq mi553 per sq mi$65,837Rockford17201
Woodford County38,111527.6 sq mi72.2 per sq mi$91,483Eureka17203

Sources: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026; US Census Bureau, Gazetteer Files, 2025 Gazetteer Files, released 10 September 2025; US Census Bureau, American Community Survey, American Community Survey 2020-2024 5-Year Estimates, released 29 January 2026; Wikidata (CC0), Wikidata. Retrieved 30 August 2026.

The ten most populous

  1. Cook County5,194,625
  2. DuPage County934,298
  3. Lake County719,339
  4. Will County712,253
  5. Kane County525,757
  6. McHenry County317,751
  7. Winnebago County283,674
  8. Madison County263,110
  9. St. Clair County250,708
  10. Champaign County209,972

Data on this page last rebuilt 30 August 2026. How these figures are produced.