# Counties in Illinois by population, 2025

All 102 values come from U.S. Census Bureau for 2025, so the places are comparable.

- Indicator id: `population`
- Unit: persons
- Definition: Resident population. Spain and the EU: 1 January, with Spanish figures from the official municipal register (Padrón). United States: Census Bureau population estimates for 1 July. Other countries and the World: World Bank mid-year estimates, which count all residents regardless of legal status or citizenship.
- Source: U.S. Census Bureau, Annual estimates of the resident population for the United States, states and counties, 1 July (Population Estimates Program) (https://www2.census.gov/programs-surveys/popest/datasets/2020-2025/)
- Retrieved: 2026-10-08
- Citation: U.S. Census Bureau. Annual estimates of the resident population for the United States, states and counties, 1 July (Population Estimates Program). https://www2.census.gov/programs-surveys/popest/datasets/2020-2025/. Retrieved 2026-10-08.
- Web page: https://invokely.ai/rankings/population/illinois-counties
- CSV: https://invokely.ai/download/rankings/population/illinois-counties.csv

| Rank | Place | persons |
|---:|---|---:|
| 1 | Cook County | 5,194,625 |
| 2 | DuPage County | 934,298 |
| 3 | Lake County | 719,339 |
| 4 | Will County | 712,253 |
| 5 | Kane County | 525,757 |
| 6 | McHenry County | 317,751 |
| 7 | Winnebago County | 283,674 |
| 8 | Madison County | 263,110 |
| 9 | St. Clair County | 250,708 |
| 10 | Champaign County | 209,972 |
| 11 | Sangamon County | 194,170 |
| 12 | Peoria County | 178,553 |
| 13 | McLean County | 171,419 |
| 14 | Kendall County | 145,470 |
| 15 | Rock Island County | 141,869 |
| 16 | Tazewell County | 130,049 |
| 17 | LaSalle County | 107,773 |
| 18 | Kankakee County | 105,525 |
| 19 | DeKalb County | 101,835 |
| 20 | Macon County | 99,300 |
| 21 | Vermilion County | 71,259 |
| 22 | Williamson County | 67,225 |
| 23 | Adams County | 64,267 |
| 24 | Whiteside County | 54,121 |
| 25 | Grundy County | 54,052 |
| 26 | Boone County | 53,568 |
| 27 | Jackson County | 52,501 |
| 28 | Ogle County | 51,399 |
| 29 | Henry County | 48,095 |
| 30 | Knox County | 47,767 |
| 31 | Coles County | 46,607 |
| 32 | Macoupin County | 43,748 |
| 33 | Stephenson County | 43,220 |
| 34 | Woodford County | 38,111 |
| 35 | Clinton County | 37,128 |
| 36 | Franklin County | 36,916 |
| 37 | Marion County | 36,382 |
| 38 | Jefferson County | 36,147 |
| 39 | Livingston County | 35,057 |
| 40 | Monroe County | 34,840 |
| 41 | Effingham County | 34,519 |
| 42 | Christian County | 33,443 |
| 43 | Lee County | 32,914 |
| 44 | Fulton County | 32,901 |
| 45 | Morgan County | 32,515 |
| 46 | Bureau County | 32,510 |
| 47 | Randolph County | 29,921 |
| 48 | Montgomery County | 28,076 |
| 49 | Logan County | 27,182 |
| 50 | Iroquois County | 26,150 |
| 51 | McDonough County | 25,916 |
| 52 | Saline County | 22,772 |
| 53 | Jo Daviess County | 21,594 |
| 54 | Jersey County | 21,160 |
| 55 | Fayette County | 20,790 |
| 56 | Shelby County | 20,576 |
| 57 | Perry County | 20,160 |
| 58 | Douglas County | 19,880 |
| 59 | Crawford County | 18,648 |
| 60 | Bond County | 16,959 |
| 61 | Hancock County | 16,803 |
| 62 | Piatt County | 16,791 |
| 63 | Union County | 16,656 |
| 64 | Edgar County | 16,323 |
| 65 | Warren County | 16,222 |
| 66 | Wayne County | 15,882 |
| 67 | Carroll County | 15,419 |
| 68 | Mercer County | 15,229 |
| 69 | Richland County | 15,219 |
| 70 | De Witt County | 15,118 |
| 71 | Clark County | 15,114 |
| 72 | Moultrie County | 14,371 |
| 73 | Pike County | 14,231 |
| 74 | Lawrence County | 13,790 |
| 75 | Washington County | 13,564 |
| 76 | Massac County | 13,502 |
| 77 | Johnson County | 13,363 |
| 78 | White County | 13,250 |
| 79 | Ford County | 13,216 |
| 80 | Clay County | 12,793 |
| 81 | Cass County | 12,463 |
| 82 | Mason County | 12,411 |
| 83 | Menard County | 11,863 |
| 84 | Marshall County | 11,473 |
| 85 | Greene County | 11,313 |
| 86 | Wabash County | 10,907 |
| 87 | Cumberland County | 10,208 |
| 88 | Jasper County | 9,032 |
| 89 | Hamilton County | 7,859 |
| 90 | Schuyler County | 6,657 |
| 91 | Brown County | 6,401 |
| 92 | Henderson County | 5,984 |
| 93 | Edwards County | 5,898 |
| 94 | Putnam County | 5,619 |
| 95 | Stark County | 5,319 |
| 96 | Scott County | 4,866 |
| 97 | Pulaski County | 4,820 |
| 98 | Gallatin County | 4,616 |
| 99 | Alexander County | 4,570 |
| 100 | Calhoun County | 4,300 |
| 101 | Pope County | 3,672 |
| 102 | Hardin County | 3,588 |