Illinois Population By County in 2021
Updated on January 29, 2024.
Based on the US Census Vintage data estimates, in 2021, the population of Illinois was 12,686,469. Among all Illinois counties, Cook[object Promise] had the highest population (5,177,606), followed by DuPage[object Promise] (926,448), and Lake[object Promise] (712,160). Hardin[object Promise] was the least populated county (3,650).
Hover over or click on the counties in the map below to see the populations. The data can also be found in a table below. You can use the table to sort, filter, and explore the data further.
You can see similar information for other states and by state for the United States.
Related Topics: Illinois Census Vintage Data Topic List.
Data Source: US Census Bureau (Vintage).
See this for other years:
Illinois Population By County in 2021
Illinois Population By County in 2021
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| County | Population | % of State Population |
|---|---|---|
| Adams | 65146 | 0.51 |
| Alexander | 5032 | 0.04 |
| Bond | 16633 | 0.13 |
| Boone | 53199 | 0.42 |
| Brown | 6443 | 0.05 |
| Bureau | 32961 | 0.26 |
| Calhoun | 4385 | 0.04 |
| Carroll | 15674 | 0.12 |
| Cass | 12798 | 0.10 |
| Champaign | 206708 | 1.63 |
| Christian | 33721 | 0.27 |
| Clark | 15354 | 0.12 |
| Clay | 13154 | 0.10 |
| Clinton | 36886 | 0.29 |
| Coles | 46809 | 0.37 |
| Cook | 5177606 | 40.81 |
| Crawford | 18691 | 0.15 |
| Cumberland | 10343 | 0.08 |
| DeKalb | 100472 | 0.79 |
| De Witt | 15379 | 0.12 |
| Douglas | 19740 | 0.16 |
| DuPage | 926448 | 7.30 |
| Edgar | 16589 | 0.13 |
| Edwards | 6086 | 0.05 |
| Effingham | 34531 | 0.27 |
| Fayette | 21447 | 0.17 |
| Ford | 13491 | 0.11 |
| Franklin | 37498 | 0.30 |
| Fulton | 33313 | 0.26 |
| Gallatin | 4907 | 0.04 |
| Greene | 11851 | 0.09 |
| Grundy | 52929 | 0.42 |
| Hamilton | 7923 | 0.06 |
| Hancock | 17388 | 0.14 |
| Hardin | 3650 | 0.03 |
| Henderson | 6304 | 0.05 |
| Henry | 48868 | 0.39 |
| Iroquois | 26761 | 0.21 |
| Jackson | 52666 | 0.42 |
| Jasper | 9204 | 0.07 |
| Jefferson | 36882 | 0.29 |
| Jersey | 21370 | 0.17 |
| Jo Daviess | 21932 | 0.17 |
| Johnson | 13471 | 0.11 |
| Kane | 516183 | 4.07 |
| Kankakee | 106652 | 0.84 |
| Kendall | 134948 | 1.06 |
| Knox | 49347 | 0.39 |
| Lake | 712160 | 5.61 |
| LaSalle | 109139 | 0.86 |
| Lawrence | 15216 | 0.12 |
| Lee | 34166 | 0.27 |
| Livingston | 35741 | 0.28 |
| Logan | 27970 | 0.22 |
| McDonough | 26848 | 0.21 |
| McHenry | 311592 | 2.46 |
| McLean | 171190 | 1.35 |
| Macon | 102649 | 0.81 |
| Macoupin | 44545 | 0.35 |
| Madison | 264898 | 2.09 |
| Marion | 37378 | 0.30 |
| Marshall | 11686 | 0.09 |
| Mason | 12859 | 0.10 |
| Massac | 13966 | 0.11 |
| Menard | 12184 | 0.10 |
| Mercer | 15568 | 0.12 |
| Monroe | 34993 | 0.28 |
| Montgomery | 28154 | 0.22 |
| Morgan | 32599 | 0.26 |
| Moultrie | 14509 | 0.11 |
| Ogle | 51474 | 0.41 |
| Peoria | 179764 | 1.42 |
| Perry | 21033 | 0.17 |
| Piatt | 16781 | 0.13 |
| Pike | 14609 | 0.12 |
| Pope | 3770 | 0.03 |
| Pulaski | 5073 | 0.04 |
| Putnam | 5596 | 0.04 |
| Randolph | 30219 | 0.24 |
| Richland | 15685 | 0.12 |
| Rock Island | 142992 | 1.13 |
| St. Clair | 255022 | 2.01 |
| Saline | 23348 | 0.18 |
| Sangamon | 195422 | 1.54 |
| Schuyler | 6822 | 0.05 |
| Scott | 4855 | 0.04 |
| Shelby | 20861 | 0.16 |
| Stark | 5296 | 0.04 |
| Stephenson | 44071 | 0.35 |
| Tazewell | 130563 | 1.03 |
| Union | 16937 | 0.13 |
| Vermilion | 73263 | 0.58 |
| Wabash | 11210 | 0.09 |
| Warren | 16595 | 0.13 |
| Washington | 13651 | 0.11 |
| Wayne | 15967 | 0.13 |
| White | 13768 | 0.11 |
| Whiteside | 55342 | 0.44 |
| Will | 697985 | 5.50 |
| Williamson | 66943 | 0.53 |
| Winnebago | 283559 | 2.24 |
| Woodford | 38210 | 0.30 |