County facts · Population · October 24, 2026
Illinois Population by County, 2025 Census Estimates
Illinois population by county: July 2025 Census estimates for all 102 counties, change since 2020, density, and a link to each official parcel map.
Looking for Illinois population by county? The Census Bureau estimates that Illinois had 12,719,141 residents on July 1, 2025, spread across 102 counties. Cook County is the most populous, with 5,194,625 people (41% of the state), and Hardin County is the least populous, with 3,588.
The table below lists every county with its 2025 estimate, its April 2020 starting point, the change, people per square mile, and a link to its official parcel viewer.
Illinois population at a glance
- Counties: 102
- Statewide, July 1, 2025: 12,719,141 (April 1, 2020 estimates base: 12,821,741; change −102,600, −0.8%)
- Most populous: Cook County (5,194,625); least populous: Hardin County (3,588)
- Median county: about 24,344 residents (half of the counties are smaller)
- The 5 largest counties hold 64% of all Illinois residents
- Counties with 1,000,000+ residents: 1 · 100,000+: 19 · under 10,000: 15
- Statewide density: about 229 people per square mile of land
Illinois population by county, July 2025 (all 102)
| # | County | Jul 2025 | Apr 2020 | % change | People per sq mi | Parcel viewer |
|---|---|---|---|---|---|---|
| 1 | Cook County | 5,194,625 | 5,279,010 | −1.6% | 5,497 | county web map |
| 2 | DuPage County | 934,298 | 933,029 | +0.1% | 2,850 | county web map |
| 3 | Lake County | 719,339 | 714,394 | +0.7% | 1,622 | county web map |
| 4 | Will County | 712,253 | 697,361 | +2.1% | 852 | county web map |
| 5 | Kane County | 525,757 | 516,709 | +1.8% | 1,012 | county web map |
| 6 | McHenry County | 317,751 | 310,305 | +2.4% | 527 | county web map |
| 7 | Winnebago County | 283,674 | 285,351 | −0.6% | 553 | county web map |
| 8 | Madison County | 263,110 | 265,983 | −1.1% | 368 | county web map |
| 9 | St. Clair County | 250,708 | 257,617 | −2.7% | 381 | county web map |
| 10 | Champaign County | 209,972 | 206,445 | +1.7% | 211 | county web map |
| 11 | Sangamon County | 194,170 | 196,405 | −1.1% | 224 | county web map |
| 12 | Peoria County | 178,553 | 182,008 | −1.9% | 289 | county web map |
| 13 | McLean County | 171,419 | 171,226 | +0.1% | 145 | ArcGIS Experience Builder |
| 14 | Kendall County | 145,470 | 131,876 | +10.3% | 454 | county web map |
| 15 | Rock Island County | 141,869 | 144,669 | −1.9% | 332 | ArcGIS Map Viewer |
| 16 | Tazewell County | 130,049 | 131,556 | −1.1% | 201 | ArcGIS Experience Builder |
| 17 | LaSalle County | 107,773 | 109,645 | −1.7% | 95 | county web map |
| 18 | Kankakee County | 105,525 | 107,648 | −2.0% | 156 | ArcGIS Experience Builder |
| 19 | DeKalb County | 101,835 | 100,522 | +1.3% | 161 | county web map |
| 20 | Macon County | 99,300 | 103,995 | −4.5% | 171 | listed link under review |
| 21 | Vermilion County | 71,259 | 74,201 | −4.0% | 79 | BHA Maps |
| 22 | Williamson County | 67,225 | 67,163 | +0.1% | 160 | Beacon (Schneider Geospatial) |
| 23 | Adams County | 64,267 | 65,745 | −2.2% | 75 | ArcGIS Map Viewer |
| 24 | Whiteside County | 54,121 | 55,688 | −2.8% | 79 | ArcGIS Experience Builder |
| 25 | Grundy County | 54,052 | 52,559 | +2.8% | 129 | county web map |
| 26 | Boone County | 53,568 | 53,446 | +0.2% | 191 | ArcGIS Map Viewer |
| 27 | Jackson County | 52,501 | 53,347 | −1.6% | 90 | BHA Maps |
| 28 | Ogle County | 51,399 | 51,850 | −0.9% | 68 | Beacon (Schneider Geospatial) |
| 29 | Henry County | 48,095 | 49,284 | −2.4% | 58 | WTH GIS |
| 30 | Knox County | 47,767 | 49,976 | −4.4% | 67 | ArcGIS Web AppBuilder |
| 31 | Coles County | 46,607 | 47,187 | −1.2% | 92 | ArcGIS Web AppBuilder |
| 32 | Macoupin County | 43,748 | 45,044 | −2.9% | 51 | BHA Maps |
| 33 | Stephenson County | 43,220 | 44,696 | −3.3% | 77 | county web map |
| 34 | Woodford County | 38,111 | 38,456 | −0.9% | 72 | ArcGIS Experience Builder |
| 35 | Clinton County | 37,128 | 36,904 | +0.6% | 78 | ArcGIS |
| 36 | Franklin County | 36,916 | 37,801 | −2.3% | 90 | myGISonline |
| 37 | Marion County | 36,382 | 37,740 | −3.6% | 64 | ArcGIS Web AppBuilder |
| 38 | Jefferson County | 36,147 | 37,115 | −2.6% | 63 | ArcGIS |
| 39 | Livingston County | 35,057 | 35,840 | −2.2% | 34 | CAMAvision Maps |
| 40 | Monroe County | 34,840 | 34,956 | −0.3% | 90 | listed link under review |
| 41 | Effingham County | 34,519 | 34,665 | −0.4% | 72 | ArcGIS Experience Builder |
| 42 | Christian County | 33,443 | 34,041 | −1.8% | 47 | BHA Maps |
| 43 | Lee County | 32,914 | 34,152 | −3.6% | 45 | listed link under review |
| 44 | Fulton County | 32,901 | 33,681 | −2.3% | 38 | ArcGIS Web AppBuilder |
| 45 | Morgan County | 32,515 | 33,567 | −3.1% | 57 | ArcGIS |
| 46 | Bureau County | 32,510 | 33,269 | −2.3% | 37 | ArcGIS Experience Builder |
| 47 | Randolph County | 29,921 | 30,165 | −0.8% | 52 | ArcGIS Web AppBuilder |
| 48 | Montgomery County | 28,076 | 28,327 | −0.9% | 40 | Beacon (Schneider Geospatial) |
| 49 | Logan County | 27,182 | 27,988 | −2.9% | 44 | ArcGIS Experience Builder |
| 50 | Iroquois County | 26,150 | 27,066 | −3.4% | 23 | BHA Maps |
| 51 | McDonough County | 25,916 | 27,254 | −4.9% | 44 | WTH GIS |
| 52 | Saline County | 22,772 | 23,821 | −4.4% | 60 | county web map |
| 53 | Jo Daviess County | 21,594 | 22,075 | −2.2% | 36 | county web map |
| 54 | Jersey County | 21,160 | 21,516 | −1.7% | 57 | ArcGIS Experience Builder |
| 55 | Fayette County | 20,790 | 21,489 | −3.3% | 29 | ArcGIS Experience Builder |
| 56 | Shelby County | 20,576 | 20,991 | −2.0% | 27 | BHA Maps |
| 57 | Perry County | 20,160 | 20,938 | −3.7% | 46 | Beacon (Schneider Geospatial) |
| 58 | Douglas County | 19,880 | 19,746 | +0.7% | 48 | listed link under review |
| 59 | Crawford County | 18,648 | 18,655 | −0.0% | 42 | Beacon (Schneider Geospatial) |
| 60 | Bond County | 16,959 | 16,899 | +0.4% | 45 | ArcGIS Web AppBuilder |
| 61 | Hancock County | 16,803 | 17,641 | −4.8% | 21 | ArcGIS Experience Builder |
| 62 | Piatt County | 16,791 | 16,684 | +0.6% | 38 | county web map |
| 63 | Union County | 16,656 | 17,350 | −4.0% | 40 | no verified public viewer listed yet |
| 64 | Edgar County | 16,323 | 16,874 | −3.3% | 26 | BHA Maps |
| 65 | Warren County | 16,222 | 16,844 | −3.7% | 30 | ArcGIS Web AppBuilder |
| 66 | Wayne County | 15,882 | 16,189 | −1.9% | 22 | ArcGIS |
| 67 | Carroll County | 15,419 | 15,720 | −1.9% | 35 | county web map |
| 68 | Mercer County | 15,229 | 15,701 | −3.0% | 27 | myGISonline |
| 69 | Richland County | 15,219 | 15,827 | −3.8% | 42 | WTH GIS |
| 70 | De Witt County | 15,118 | 15,507 | −2.5% | 38 | ArcGIS Experience Builder |
| 71 | Clark County | 15,114 | 15,487 | −2.4% | 30 | Beacon (Schneider Geospatial) |
| 72 | Moultrie County | 14,371 | 14,530 | −1.1% | 43 | ArcGIS Experience Builder |
| 73 | Pike County | 14,231 | 14,728 | −3.4% | 17 | WTH GIS |
| 74 | Lawrence County | 13,790 | 15,301 | −9.9% | 37 | BHA Maps |
| 75 | Washington County | 13,564 | 13,765 | −1.5% | 24 | ArcGIS |
| 76 | Massac County | 13,502 | 14,176 | −4.8% | 57 | BHA Maps |
| 77 | Johnson County | 13,363 | 13,304 | +0.4% | 39 | no verified public viewer listed yet |
| 78 | White County | 13,250 | 13,872 | −4.5% | 27 | ArcGIS Experience Builder |
| 79 | Ford County | 13,216 | 13,532 | −2.3% | 27 | BHA Maps |
| 80 | Clay County | 12,793 | 13,289 | −3.7% | 27 | ArcGIS Experience Builder |
| 81 | Cass County | 12,463 | 13,037 | −4.4% | 33 | Beacon (Schneider Geospatial) |
| 82 | Mason County | 12,411 | 13,082 | −5.1% | 23 | WTH GIS |
| 83 | Menard County | 11,863 | 12,297 | −3.5% | 38 | Beacon (Schneider Geospatial) |
| 84 | Marshall County | 11,473 | 11,750 | −2.4% | 30 | myGISonline |
| 85 | Greene County | 11,313 | 11,975 | −5.5% | 21 | no verified public viewer listed yet |
| 86 | Wabash County | 10,907 | 11,361 | −4.0% | 49 | BHA Maps |
| 87 | Cumberland County | 10,208 | 10,450 | −2.3% | 30 | ArcGIS Experience Builder |
| 88 | Jasper County | 9,032 | 9,299 | −2.9% | 18 | BHA Maps |
| 89 | Hamilton County | 7,859 | 7,992 | −1.7% | 18 | ArcGIS Experience Builder |
| 90 | Schuyler County | 6,657 | 6,896 | −3.5% | 15 | ArcGIS |
| 91 | Brown County | 6,401 | 6,245 | +2.5% | 21 | myGISonline |
| 92 | Henderson County | 5,984 | 6,392 | −6.4% | 16 | county web map |
| 93 | Edwards County | 5,898 | 6,243 | −5.5% | 27 | BHA Maps |
| 94 | Putnam County | 5,619 | 5,631 | −0.2% | 35 | WTH GIS |
| 95 | Stark County | 5,319 | 5,395 | −1.4% | 18 | ArcGIS Web AppBuilder |
| 96 | Scott County | 4,866 | 5,076 | −4.1% | 19 | county web map |
| 97 | Pulaski County | 4,820 | 5,206 | −7.4% | 24 | ArcGIS Web AppBuilder |
| 98 | Gallatin County | 4,616 | 4,942 | −6.6% | 14 | WTH GIS |
| 99 | Alexander County | 4,570 | 5,239 | −12.8% | 19 | ArcGIS Map Viewer |
| 100 | Calhoun County | 4,300 | 4,430 | −2.9% | 17 | county web map |
| 101 | Pope County | 3,672 | 3,766 | −2.5% | 10.0 | no verified public viewer listed yet |
| 102 | Hardin County | 3,588 | 3,659 | −1.9% | 20 | no verified public viewer listed yet |
Percent change runs from the April 1, 2020 estimates base to July 1, 2025. People per square mile is the July 2025 estimate divided by the county's land area in the Census Bureau's 2020 Gazetteer file, so lakes and bays are left out.
How Illinois's population is spread out
Grouping the counties by size shows how concentrated the state is:
| Residents (July 2025) | Counties | Total residents | Share of state |
|---|---|---|---|
| 1,000,000 or more | 1 | 5,194,625 | 41% |
| 250,000 to 999,999 | 8 | 4,006,890 | 32% |
| 100,000 to 249,999 | 10 | 1,486,635 | 12% |
| 25,000 to 99,999 | 32 | 1,387,757 | 11% |
| 10,000 to 24,999 | 36 | 560,033 | 4% |
| Under 10,000 | 15 | 83,201 | 1% |
9 counties with at least 250,000 residents hold 72% of the state's population.
Most and least densely populated
The most crowded counties by people per square mile of land:
- Cook County: 5,497 per sq mi (5,194,625 people on 945 sq mi)
- DuPage County: 2,850 per sq mi (934,298 people on 328 sq mi)
- Lake County: 1,622 per sq mi (719,339 people on 444 sq mi)
- Kane County: 1,012 per sq mi (525,757 people on 519 sq mi)
- Will County: 852 per sq mi (712,253 people on 836 sq mi)
The most thinly settled:
- Pope County: 10.0 per sq mi (3,672 people on 369 sq mi)
- Gallatin County: 14 per sq mi (4,616 people on 323 sq mi)
- Schuyler County: 15 per sq mi (6,657 people on 437 sq mi)
- Henderson County: 16 per sq mi (5,984 people on 379 sq mi)
- Calhoun County: 17 per sq mi (4,300 people on 254 sq mi)
About these numbers
- They are estimates. Between censuses the Census Bureau's Population Estimates Program updates county totals each year from births, deaths and migration records. The next full count is the 2030 census.
- The base is April 1, 2020. The estimates start from an April 1, 2020 "estimates base" built from the 2020 census, which is why it is slightly different from the published census count.
- Each new release revises the past. A newer vintage can change earlier years as well, so compare numbers from the same release, as this page does.
- Statewide total. The counties add up exactly to the statewide figure of 12,719,141 in the same file.
Using population numbers in a land search
- Big counties, busy offices. In the most populous counties, parcel maps and deed records are usually online and searchable, but recording and permit offices are busier. Allow for that if you are on a deadline.
- Small counties, fewer sales. In counties with only a few thousand people, land changes hands less often, so there are fewer recent sales to compare a price with. The county assessor's sales records are the best source.
- Density hints at lot size. A low people-per-square-mile figure usually means farms, ranches and timber tracts; a high one means subdivided lots. The parcel viewer shows the actual parcel lines.
- Check the official map. Use the parcel viewer link in the table for boundaries, parcel numbers and owner names, then confirm anything important with the county's recorder or assessor.
Related guides
- Fastest growing counties in Illinois
- Largest counties in Illinois
- Illinois county GIS websites by viewer
- Illinois landowner maps for hunting
- Most populous counties in the US
- Where people are moving in the US
More: All Illinois counties on Platbookmapper
Sources
- U.S. Census Bureau, Population Estimates Program, county totals, Vintage 2025 (April 1, 2020 estimates base and July 1, 2020–2025 estimates, with components of change). Statewide totals are the sum of the counties and match the file's state row.
- U.S. Census Bureau Gazetteer files, 2020 county land and water area (for people per square mile).
- Platbookmapper county GIS directory (live data file behind our county pages, pulled October 24, 2026) for each official parcel viewer.