# Counties in Illinois by population aged 18 to 64, 2025

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

- Indicator id: `population_18_64_share`
- Unit: %
- Definition: Residents aged 18 to 64 as a percentage of total population on 1 July. United States: Census Bureau county population estimates by age; states and the nation are sums of their counties.
- Source: U.S. Census Bureau, Population Estimates Program, county population by age and sex: residents aged 18 to 64 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties (https://www.census.gov/programs-surveys/popest/data/data-sets.html)
- Retrieved: 2026-10-12
- Citation: U.S. Census Bureau. Population Estimates Program, county population by age and sex: residents aged 18 to 64 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties. https://www.census.gov/programs-surveys/popest/data/data-sets.html. Retrieved 2026-10-12.
- Web page: https://invokely.ai/rankings/population-18-64/illinois-counties

| Rank | Place | % |
|---:|---|---:|
| 1 | Champaign County | 66.4 |
| 2 | Brown County | 65.7 |
| 3 | Cook County | 63.4 |
| 4 | McLean County | 63.2 |
| 5 | Bond County | 62.5 |
| 6 | DeKalb County | 62.3 |
| 7 | Jackson County | 62 |
| 8 | Kendall County | 61.9 |
| 9 | Johnson County | 61.3 |
| 10 | Will County | 61 |
| 11 | Lake County | 60.3 |
| 12 | Kane County | 60.1 |
| 13 | Grundy County | 60 |
| 14 | Coles County | 59.8 |
| 15 | McHenry County | 59.6 |
| 16 | DuPage County | 59.4 |
| 17 | Logan County | 59.3 |
| 18 | McDonough County | 59.2 |
| 19 | Perry County | 59.2 |
| 20 | Lawrence County | 59.1 |
| 21 | Madison County | 58.9 |
| 22 | Boone County | 58.8 |
| 23 | Fayette County | 58.7 |
| 24 | St. Clair County | 58.6 |
| 25 | Christian County | 58.3 |
| 26 | Morgan County | 58.1 |
| 27 | Randolph County | 58.1 |
| 28 | Kankakee County | 58 |
| 29 | Crawford County | 57.9 |
| 30 | Lee County | 57.9 |
| 31 | Winnebago County | 57.7 |
| 32 | Sangamon County | 57.6 |
| 33 | Fulton County | 57.6 |
| 34 | Cass County | 57.5 |
| 35 | Clinton County | 57.5 |
| 36 | Peoria County | 57.3 |
| 37 | Montgomery County | 57.3 |
| 38 | Williamson County | 57.3 |
| 39 | Tazewell County | 57.2 |
| 40 | LaSalle County | 57 |
| 41 | Ogle County | 56.9 |
| 42 | De Witt County | 56.8 |
| 43 | Jersey County | 56.7 |
| 44 | Knox County | 56.6 |
| 45 | Carroll County | 56.2 |
| 46 | Rock Island County | 56.2 |
| 47 | Livingston County | 56.1 |
| 48 | Warren County | 56.1 |
| 49 | Macoupin County | 56 |
| 50 | Monroe County | 56 |
| 51 | Jefferson County | 55.9 |
| 52 | Massac County | 55.8 |
| 53 | Menard County | 55.7 |
| 54 | Effingham County | 55.6 |
| 55 | Adams County | 55.5 |
| 56 | Union County | 55.5 |
| 57 | Richland County | 55.5 |
| 58 | Franklin County | 55.4 |
| 59 | Vermilion County | 55.4 |
| 60 | Macon County | 55.3 |
| 61 | Saline County | 55.2 |
| 62 | Washington County | 55.2 |
| 63 | Mercer County | 55.2 |
| 64 | Bureau County | 55.2 |
| 65 | Mason County | 55.2 |
| 66 | Clark County | 55.2 |
| 67 | Douglas County | 55.1 |
| 68 | Greene County | 55 |
| 69 | Pulaski County | 55 |
| 70 | Ford County | 54.8 |
| 71 | Putnam County | 54.8 |
| 72 | Gallatin County | 54.8 |
| 73 | White County | 54.8 |
| 74 | Wabash County | 54.7 |
| 75 | Whiteside County | 54.6 |
| 76 | Henry County | 54.6 |
| 77 | Woodford County | 54.6 |
| 78 | Hamilton County | 54.5 |
| 79 | Schuyler County | 54.5 |
| 80 | Stark County | 54.4 |
| 81 | Piatt County | 54.4 |
| 82 | Marion County | 54.4 |
| 83 | Wayne County | 54.3 |
| 84 | Edwards County | 54.3 |
| 85 | Cumberland County | 54.2 |
| 86 | Scott County | 54.2 |
| 87 | Pope County | 54.2 |
| 88 | Iroquois County | 54 |
| 89 | Clay County | 54 |
| 90 | Edgar County | 54 |
| 91 | Marshall County | 53.9 |
| 92 | Pike County | 53.9 |
| 93 | Jasper County | 53.6 |
| 94 | Moultrie County | 53.5 |
| 95 | Stephenson County | 53.5 |
| 96 | Shelby County | 53.5 |
| 97 | Alexander County | 53.2 |
| 98 | Calhoun County | 52.3 |
| 99 | Hancock County | 52.3 |
| 100 | Henderson County | 51.7 |
| 101 | Jo Daviess County | 50.8 |
| 102 | Hardin County | 49.2 |