Illinois Population By County in 2021 (ACS-5Yrs)
Updated on July 2, 2024.
Based on the US Census ACS-5Yrs estimates, in 2021, the total population of Illinois was 12.82M. Among all Illinois counties, Cook was the most populated county (5.27M), followed by DuPage (934.09K), and then Lake (714.48K).
On the other hand, the least populated counties were: Hardin (3.70K), Pope (3.82K), and Calhoun (4.54K).
The chart and table below shows the population of each county and the percentage of Illinois population in each county.
You can see similar information for other states and by state for the United States.
Related Topics: Illinois ACS-5Yrs Estimates, 2021 Topic List.
Data Source: US Census - ACS 5-Year Estimates, 2021 Census.
Illinois Population By County in 2021
Illinois Population By County in 2021
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| County | Population | % of State Population |
|---|---|---|
| Adams | 65878 | 0.51 |
| Alexander | 5488 | 0.04 |
| Bond | 16804 | 0.13 |
| Boone | 53592 | 0.42 |
| Brown | 6330 | 0.05 |
| Bureau | 33338 | 0.26 |
| Calhoun | 4537 | 0.04 |
| Carroll | 15586 | 0.12 |
| Cass | 13058 | 0.10 |
| Champaign | 206583 | 1.61 |
| Christian | 34038 | 0.27 |
| Clark | 15587 | 0.12 |
| Clay | 13313 | 0.10 |
| Clinton | 37048 | 0.29 |
| Coles | 47542 | 0.37 |
| Cook | 5265398 | 41.07 |
| Crawford | 18825 | 0.15 |
| Cumberland | 10528 | 0.08 |
| DeKalb | 100922 | 0.79 |
| De Witt | 15653 | 0.12 |
| Douglas | 19708 | 0.15 |
| DuPage | 934094 | 7.29 |
| Edgar | 16998 | 0.13 |
| Edwards | 6233 | 0.05 |
| Effingham | 34576 | 0.27 |
| Fayette | 21514 | 0.17 |
| Ford | 13589 | 0.11 |
| Franklin | 38068 | 0.30 |
| Fulton | 34022 | 0.27 |
| Gallatin | 5038 | 0.04 |
| Greene | 12187 | 0.10 |
| Grundy | 52364 | 0.41 |
| Hamilton | 8021 | 0.06 |
| Hancock | 17750 | 0.14 |
| Hardin | 3700 | 0.03 |
| Henderson | 6485 | 0.05 |
| Henry | 49412 | 0.39 |
| Iroquois | 27362 | 0.21 |
| Jackson | 53676 | 0.42 |
| Jasper | 9324 | 0.07 |
| Jefferson | 37362 | 0.29 |
| Jersey | 21533 | 0.17 |
| Jo Daviess | 21995 | 0.17 |
| Johnson | 13238 | 0.10 |
| Kane | 518648 | 4.05 |
| Kankakee | 108104 | 0.84 |
| Kendall | 130757 | 1.02 |
| Knox | 50193 | 0.39 |
| Lake | 714484 | 5.57 |
| LaSalle | 109986 | 0.86 |
| Lawrence | 15465 | 0.12 |
| Lee | 34373 | 0.27 |
| Livingston | 35902 | 0.28 |
| Logan | 28238 | 0.22 |
| McDonough | 27743 | 0.22 |
| McHenry | 310749 | 2.42 |
| McLean | 171455 | 1.34 |
| Macon | 104331 | 0.81 |
| Macoupin | 45152 | 0.35 |
| Madison | 266112 | 2.08 |
| Marion | 37781 | 0.30 |
| Marshall | 11781 | 0.09 |
| Mason | 13225 | 0.10 |
| Massac | 14280 | 0.11 |
| Menard | 12343 | 0.10 |
| Mercer | 15779 | 0.12 |
| Monroe | 34732 | 0.27 |
| Montgomery | 28482 | 0.22 |
| Morgan | 33189 | 0.26 |
| Moultrie | 14634 | 0.11 |
| Ogle | 51787 | 0.40 |
| Peoria | 182439 | 1.42 |
| Perry | 21158 | 0.17 |
| Piatt | 16664 | 0.13 |
| Pike | 14923 | 0.12 |
| Pope | 3820 | 0.03 |
| Pulaski | 5279 | 0.04 |
| Putnam | 5638 | 0.04 |
| Randolph | 30632 | 0.24 |
| Richland | 15876 | 0.12 |
| Rock Island | 144694 | 1.13 |
| St. Clair | 258597 | 2.02 |
| Saline | 23869 | 0.19 |
| Sangamon | 196759 | 1.54 |
| Schuyler | 6953 | 0.05 |
| Scott | 4923 | 0.04 |
| Shelby | 21160 | 0.17 |
| Stark | 5436 | 0.04 |
| Stephenson | 44817 | 0.35 |
| Tazewell | 131977 | 1.03 |
| Union | 17259 | 0.14 |
| Vermilion | 74953 | 0.59 |
| Wabash | 11414 | 0.09 |
| Warren | 16887 | 0.13 |
| Washington | 13827 | 0.11 |
| Wayne | 16250 | 0.13 |
| White | 13959 | 0.11 |
| Whiteside | 55932 | 0.44 |
| Will | 696403 | 5.43 |
| Williamson | 67271 | 0.53 |
| Winnebago | 285471 | 2.23 |
| Woodford | 38571 | 0.30 |