Counties in Illinois
Illinois has 102 counties. Find yours from your location, or explore the map and the full list with seats, population, time zones and FIPS codes.
Updated · Data: U.S. Census Bureau
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Illinois has 102 counties, home to about 12,692,653 people. Sort the table by any column, or search by name or seat.
Counties102Central time
Most peopleCook County5,185,812 residents, 41% of the state
Fewest peopleHardin County3,623 residents
Most crowdedCook County5,488 people per sq mi
Largest by landMcLean County1,183.2 sq mi
Priciest homesDuPage Countymedian value $374,100
Illinois county map
Population3.6k8.0k14k17k33k47k131kno data
County explorer: all 102 counties in Illinois
| County | Seat | Population | Land sq mi | People / sq mi | Median home | Time zone | FIPS |
|---|---|---|---|---|---|---|---|
| Cook | Chicago | 5,185,812 | 944.9 | 5,488 | $305,200 | Central | 17031 |
| DuPage | Wheaton | 927,263 | 327.8 | 2,829 | $374,100 | Central | 17043 |
| Lake | Waukegan | 711,885 | 443.7 | 1,604 | $326,600 | Central | 17097 |
| Will | Joliet | 698,450 | 835.9 | 836 | $298,000 | Central | 17197 |
| Kane | Geneva | 516,097 | 519.3 | 994 | $303,000 | Central | 17089 |
| McHenry | Woodstock | 311,366 | 603.4 | 516 | $286,900 | Central | 17111 |
| Winnebago | Rockford | 283,289 | 513.0 | 552 | $155,100 | Central | 17201 |
| Madison | Edwardsville | 264,631 | 715.5 | 370 | $167,900 | Central | 17119 |
| St. Clair | Belleville | 254,777 | 657.7 | 387 | $168,800 | Central | 17163 |
| Champaign | Urbana | 206,098 | 996.1 | 207 | $205,100 | Central | 17019 |
| Sangamon | Springfield | 195,217 | 868.2 | 225 | $170,300 | Central | 17167 |
| Peoria | Peoria | 179,831 | 618.7 | 291 | $152,600 | Central | 17143 |
| McLean | Bloomington | 170,882 | 1,183.2 | 144 | $198,300 | Central | 17113 |
| Rock Island | Rock Island | 142,995 | 427.5 | 334 | $144,700 | Central | 17161 |
| Kendall | Yorkville | 135,053 | 320.2 | 422 | $298,900 | Central | 17093 |
| Tazewell | Pekin | 130,555 | 646.5 | 202 | $164,500 | Central | 17179 |
| LaSalle | Ottawa | 109,049 | 1,135.1 | 96 | $154,900 | Central | 17099 |
| Kankakee | Kankakee | 106,833 | 676.5 | 158 | $185,700 | Central | 17091 |
| Macon | Decatur | 102,591 | 580.5 | 177 | $121,800 | Central | 17115 |
| DeKalb | Sycamore | 100,512 | 631.3 | 159 | $231,900 | Central | 17037 |
| Vermilion | Danville | 73,179 | 898.3 | 81 | $92,900 | Central | 17183 |
| Williamson | Marion | 66,902 | 420.2 | 159 | $145,600 | Central | 17199 |
| Adams | - | 65,166 | 855.2 | 76 | $155,900 | Central | 17001 |
| Whiteside | Morrison | 55,192 | 684.1 | 81 | $125,800 | Central | 17195 |
| Boone | Belvidere | 53,316 | 280.7 | 190 | $198,600 | Central | 17007 |
| Grundy | Morris | 52,920 | 418.1 | 127 | $259,200 | Central | 17063 |
| Jackson | Murphysboro | 52,706 | 583.6 | 90 | $125,000 | Central | 17077 |
| Ogle | Oregon | 51,536 | 758.7 | 68 | $184,100 | Central | 17141 |
| Knox | Galesburg | 49,294 | 716.4 | 69 | $104,900 | Central | 17095 |
| Henry | Cambridge | 48,948 | 823.1 | 59 | $145,300 | Central | 17073 |
| Coles | Charleston | 46,689 | 508.3 | 92 | $121,900 | Central | 17029 |
| Macoupin | Carlinville | 44,566 | 863.0 | 52 | $126,100 | Central | 17117 |
| Stephenson | Freeport | 44,042 | 564.2 | 78 | $127,500 | Central | 17177 |
| Woodford | Eureka | 38,348 | 527.6 | 73 | $193,800 | Central | 17203 |
| Franklin | Benton, Illinois | 37,541 | 408.9 | 92 | $87,700 | Central | 17055 |
| Marion | Salem | 37,294 | 572.5 | 65 | $100,100 | Central | 17121 |
| Clinton | Carlyle | 36,899 | 473.9 | 78 | $180,500 | Central | 17027 |
| Jefferson | Mount Vernon | 36,808 | 571.2 | 64 | $118,400 | Central | 17081 |
| Livingston | Pontiac | 35,659 | 1,043.6 | 34 | $131,500 | Central | 17105 |
| Monroe | Waterloo | 34,969 | 385.3 | 91 | $265,600 | Central | 17133 |
| Effingham | Effingham | 34,505 | 478.8 | 72 | $179,800 | Central | 17049 |
| Lee | Dixon | 34,058 | 724.8 | 47 | $155,100 | Central | 17103 |
| Christian | Taylorville | 33,684 | 709.5 | 47 | $112,100 | Central | 17021 |
| Fulton | Lewistown | 33,259 | 865.7 | 38 | $102,500 | Central | 17057 |
| Bureau | Princeton | 33,027 | 869.1 | 38 | $121,900 | Central | 17011 |
| Morgan | Jacksonville | 32,621 | 569.0 | 57 | $128,700 | Central | 17137 |
| Randolph | Chester | 30,142 | 575.4 | 52 | $134,100 | Central | 17157 |
| Montgomery | Hillsboro | 28,078 | 703.8 | 40 | $102,200 | Central | 17135 |
| Logan | Lincoln | 27,870 | 618.1 | 45 | $125,900 | Central | 17107 |
| McDonough | Macomb | 27,102 | 589.3 | 46 | $103,500 | Central | 17109 |
| Iroquois | Watseka | 26,746 | 1,117.4 | 24 | $125,400 | Central | 17075 |
| Saline | Harrisburg | 23,387 | 380.0 | 62 | $92,900 | Central | 17165 |
| Jo Daviess | Galena | 21,918 | 600.9 | 36 | $193,900 | Central | 17085 |
| Fayette | Vandalia | 21,380 | 716.4 | 30 | $114,700 | Central | 17051 |
| Jersey | Jerseyville | 21,336 | 369.6 | 58 | $168,800 | Central | 17083 |
| Shelby | Shelbyville | 20,867 | 758.5 | 28 | $130,400 | Central | 17173 |
| Perry | Pinckneyville | 20,810 | 441.9 | 47 | $105,200 | Central | 17145 |
| Douglas | Tuscola | 19,686 | 416.6 | 47 | $142,600 | Central | 17041 |
| Crawford | Robinson | 18,588 | 443.6 | 42 | $113,700 | Central | 17033 |
| Hancock | Carthage | 17,434 | 793.7 | 22 | $108,400 | Central | 17067 |
| Union | Jonesboro | 16,972 | 413.4 | 41 | $131,700 | Central | 17181 |
| Piatt | Monticello | 16,702 | 439.2 | 38 | $173,200 | Central | 17147 |
| Edgar | Paris | 16,637 | 623.3 | 27 | $95,700 | Central | 17045 |
| Bond | Greenville | 16,627 | 380.3 | 44 | $133,100 | Central | 17005 |
| Warren | Monmouth | 16,576 | 542.3 | 31 | $101,300 | Central | 17187 |
| Wayne | Fairfield | 15,994 | 713.8 | 22 | $109,400 | Central | 17191 |
| Richland | Olney | 15,675 | 360.0 | 44 | $106,600 | Central | 17159 |
| Carroll | Mount Carroll | 15,621 | 445.4 | 35 | $113,500 | Central | 17015 |
| Mercer | Aledo | 15,619 | 561.2 | 28 | $139,300 | Central | 17131 |
| De Witt | Clinton | 15,461 | 397.6 | 39 | $124,200 | Central | 17039 |
| Clark | Marshall | 15,328 | 501.4 | 31 | $123,100 | Central | 17023 |
| Lawrence | Lawrenceville | 15,137 | 372.2 | 41 | $95,500 | Central | 17101 |
| Pike | Pittsfield | 14,625 | 831.4 | 18 | $100,100 | Central | 17149 |
| Moultrie | Sullivan | 14,469 | 336.0 | 43 | $121,500 | Central | 17139 |
| Massac | Metropolis | 13,958 | 237.2 | 59 | $118,000 | Central | 17127 |
| White | Carmi | 13,708 | 495.0 | 28 | $100,100 | Central | 17193 |
| Washington | Nashville | 13,682 | 562.6 | 24 | $149,800 | Central | 17189 |
| Ford | Paxton | 13,396 | 485.6 | 28 | $118,100 | Central | 17053 |
| Johnson | Vienna | 13,350 | 343.7 | 39 | $148,200 | Central | 17087 |
| Clay | Louisville | 13,173 | 468.4 | 28 | $94,300 | Central | 17025 |
| Mason | Havana | 12,878 | 539.4 | 24 | $106,100 | Central | 17125 |
| Cass | Virginia | 12,826 | 375.8 | 34 | $95,500 | Central | 17017 |
| Menard | Petersburg | 12,169 | 314.4 | 39 | $179,300 | Central | 17129 |
| Greene | Carrollton | 11,837 | 543.1 | 22 | $94,400 | Central | 17061 |
| Marshall | Lacon | 11,715 | 386.8 | 30 | $137,800 | Central | 17123 |
| Wabash | Mount Carmel | 11,199 | 223.3 | 50 | $103,900 | Central | 17185 |
| Cumberland | Toledo | 10,378 | 345.9 | 30 | $117,700 | Central | 17035 |
| Jasper | Newton | 9,233 | 494.6 | 19 | $122,900 | Central | 17079 |
| Hamilton | McLeansboro | 7,972 | 434.6 | 18 | $108,800 | Central | 17065 |
| Schuyler | Rushville | 6,826 | 437.3 | 16 | $106,200 | Central | 17169 |
| Brown | Mount Sterling | 6,320 | 305.7 | 21 | $142,200 | Central | 17009 |
| Henderson | Oquawka | 6,284 | 378.8 | 17 | $101,600 | Central | 17071 |
| Edwards | Albion | 6,118 | 222.4 | 28 | $97,500 | Central | 17047 |
| Putnam | Hennepin | 5,600 | 160.1 | 35 | $167,800 | Central | 17155 |
| Stark | Toulon | 5,324 | 288.1 | 18 | $103,500 | Central | 17175 |
| Pulaski | Mound City | 5,074 | 199.3 | 25 | $81,000 | Central | 17153 |
| Alexander | Cairo | 5,042 | 235.4 | 21 | $58,700 | Central | 17003 |
| Gallatin | Shawneetown | 4,857 | 322.9 | 15 | $84,700 | Central | 17059 |
| Scott | Winchester | 4,847 | 250.8 | 19 | $101,700 | Central | 17171 |
| Calhoun | Hardin | 4,406 | 253.8 | 17 | $174,000 | Central | 17013 |
| Pope | Golconda | 3,757 | 368.9 | 10 | $165,300 | Central | 17151 |
| Hardin | Elizabethtown | 3,623 | 177.4 | 20 | $91,700 | Central | 17069 |
Which Illinois cities are in more than one county?
- Aurora: Kane County 61.7%, DuPage County 28.5%, Will County 6.5%, Kendall County 3.3% of residents
- Joliet: Will County 90.9%, Kendall County 9.1% of residents
- Naperville: DuPage County 65.7%, Will County 34.3% of residents
- Elgin: Kane County 78.7%, Cook County 21.3% of residents
- Bolingbrook: Will County 98.2%, DuPage County 1.8% of residents
- Orland Park: Cook County 99.4%, Will County 0.6% of residents
- Tinley Park: Cook County 86.1%, Will County 13.9% of residents
- Plainfield: Will County 93.0%, Kendall County 7.0% of residents
- Buffalo Grove: Lake County 68.3%, Cook County 31.7% of residents
- Bartlett: DuPage County 58.3%, Cook County 41.7% of residents
- Hanover Park: Cook County 53.3%, DuPage County 46.7% of residents
- Woodridge: DuPage County 99.9%, Will County 0.1% of residents
Sources: Census TIGER/Line 2024; ACS 2019-2023 5-year; Wikidata, CC0 (seats); timezone-boundary-builder (time zones). Data as of November 1, 2026. Not affiliated with any government agency.
FAQ
Frequently asked questions
How many counties are in Illinois?
102.
What is the most populated county in Illinois?
Cook County, with about 5,185,812 people (41% of the state).
What is the least populated county in Illinois?
Hardin County, with about 3,623 people.
What is the largest county in Illinois by land?
McLean County, 1,183.2 sq mi of land.
What county am I in, in Illinois?
Use the tool at the top of this page: press Use my current location, or type your city or ZIP code.