Fastest growing counties in Illinois.
County | Rank | Change (2020) | 2024 Pop. | 2020 Pop. |
|---|---|---|---|---|
| Kendall County | 1 | 7.63% | 142,458 | 132,355 |
| Grundy County | 2 | 2.84% | 54,007 | 52,516 |
| McHenry County | 3 | 1.34% | 314,042 | 309,882 |
| Will County | 4 | 0.94% | 703,410 | 696,826 |
| Brown County | 5 | 0.72% | 6,272 | 6,227 |
| Piatt County | 6 | 0.43% | 16,753 | 16,681 |
| DeKalb County | 7 | 0.08% | 100,353 | 100,269 |
| Boone County | 8 | -0.01% | 53,336 | 53,343 |
| Woodford County | 9 | -0.05% | 38,393 | 38,413 |
| Kane County | 10 | -0.07% | 515,825 | 516,181 |
| Monroe County | 11 | -0.11% | 34,913 | 34,953 |
| Marshall County | 12 | -0.19% | 11,695 | 11,717 |
| Champaign County | 13 | -0.26% | 205,119 | 205,654 |
| Williamson County | 14 | -0.37% | 66,868 | 67,114 |
| Johnson County | 15 | -0.43% | 13,261 | 13,318 |
| McLean County | 16 | -0.58% | 169,964 | 170,949 |
| De Witt County | 17 | -0.62% | 15,365 | 15,461 |
| Clinton County | 18 | -0.73% | 36,633 | 36,901 |
| Lake County | 19 | -0.79% | 707,621 | 713,281 |
| Douglas County | 20 | -0.88% | 19,591 | 19,764 |
| LaSalle County | 21 | -0.89% | 108,437 | 109,410 |
| Ogle County | 22 | -0.98% | 51,185 | 51,692 |
| Effingham County | 23 | -0.98% | 34,362 | 34,703 |
| Putnam County | 24 | -1.08% | 5,569 | 5,630 |
| DuPage County | 25 | -1.13% | 920,762 | 931,317 |
| Moultrie County | 26 | -1.19% | 14,309 | 14,481 |
| Mercer County | 27 | -1.22% | 15,441 | 15,632 |
| Tazewell County | 28 | -1.23% | 129,472 | 131,086 |
| McDonough County | 29 | -1.24% | 26,764 | 27,100 |
| Carroll County | 30 | -1.27% | 15,473 | 15,672 |
| Kankakee County | 31 | -1.29% | 105,882 | 107,264 |
| Jasper County | 32 | -1.35% | 9,116 | 9,241 |
| Madison County | 33 | -1.4% | 261,932 | 265,643 |
| Logan County | 34 | -1.43% | 27,514 | 27,912 |
| Randolph County | 35 | -1.62% | 29,604 | 30,090 |
| Winnebago County | 36 | -1.62% | 280,302 | 284,916 |
| Franklin County | 37 | -1.69% | 37,061 | 37,697 |
| Bureau County | 38 | -1.69% | 32,631 | 33,191 |
| Sangamon County | 39 | -1.69% | 192,831 | 196,144 |
| Henry County | 40 | -1.76% | 48,300 | 49,167 |
| Jo Daviess County | 41 | -1.77% | 21,667 | 22,057 |
| Livingston County | 42 | -1.87% | 35,123 | 35,792 |
| Perry County | 43 | -1.88% | 20,494 | 20,886 |
| Bond County | 44 | -1.92% | 16,364 | 16,684 |
| Adams County | 45 | -1.96% | 64,326 | 65,614 |
| Hamilton County | 46 | -1.98% | 7,841 | 7,999 |
| Ford County | 47 | -1.99% | 13,244 | 13,513 |
| Washington County | 48 | -2% | 13,449 | 13,723 |
| Fayette County | 49 | -2.01% | 21,058 | 21,490 |
| Whiteside County | 50 | -2.02% | 54,441 | 55,565 |
| Lee County | 51 | -2.03% | 33,370 | 34,062 |
| Jackson County | 52 | -2.05% | 51,805 | 52,891 |
| Hardin County | 53 | -2.09% | 3,566 | 3,642 |
| Jefferson County | 54 | -2.09% | 36,221 | 36,995 |
| Cumberland County | 55 | -2.1% | 10,214 | 10,433 |
| Macoupin County | 56 | -2.1% | 43,913 | 44,856 |
| Coles County | 57 | -2.11% | 45,774 | 46,760 |
| Schuyler County | 58 | -2.26% | 6,713 | 6,868 |
| Pope County | 59 | -2.29% | 3,668 | 3,754 |
| Richland County | 60 | -2.34% | 15,421 | 15,790 |
| Jersey County | 61 | -2.34% | 20,991 | 21,494 |
| Shelby County | 62 | -2.36% | 20,426 | 20,919 |
| Peoria County | 63 | -2.37% | 177,026 | 181,319 |
| Rock Island County | 64 | -2.39% | 140,913 | 144,360 |
| Hancock County | 65 | -2.42% | 17,118 | 17,543 |
| Morgan County | 66 | -2.63% | 31,982 | 32,845 |
| Christian County | 67 | -2.63% | 33,066 | 33,960 |
| Clay County | 68 | -2.65% | 12,921 | 13,273 |
| Clark County | 69 | -2.68% | 15,016 | 15,429 |
| St. Clair County | 70 | -2.75% | 249,771 | 256,844 |
| Montgomery County | 71 | -2.76% | 27,425 | 28,202 |
| Wayne County | 72 | -2.77% | 15,679 | 16,126 |
| Calhoun County | 73 | -2.86% | 4,281 | 4,407 |
| Crawford County | 74 | -2.93% | 18,105 | 18,651 |
| Edgar County | 75 | -3% | 16,283 | 16,786 |
| Pike County | 76 | -3.11% | 14,185 | 14,640 |
| Knox County | 77 | -3.19% | 48,202 | 49,790 |
| Marion County | 78 | -3.22% | 36,441 | 37,652 |
| Cass County | 79 | -3.36% | 12,554 | 12,991 |
| Lawrence County | 80 | -3.49% | 14,735 | 15,268 |
| Menard County | 81 | -3.54% | 11,836 | 12,270 |
| Union County | 82 | -3.62% | 16,562 | 17,184 |
| Macon County | 83 | -3.76% | 99,849 | 103,752 |
| Vermilion County | 84 | -3.79% | 71,201 | 74,009 |
| Cook County | 85 | -3.82% | 5,062,578 | 5,263,608 |
| Fulton County | 86 | -4% | 32,147 | 33,487 |
| Greene County | 87 | -4.11% | 11,446 | 11,936 |
| Stephenson County | 88 | -4.15% | 42,654 | 44,503 |
| Wabash County | 89 | -4.19% | 10,844 | 11,318 |
| Saline County | 90 | -4.2% | 22,694 | 23,690 |
| White County | 91 | -4.35% | 13,207 | 13,808 |
| Iroquois County | 92 | -4.47% | 25,779 | 26,984 |
| Massac County | 93 | -4.51% | 13,495 | 14,133 |
| Stark County | 94 | -4.81% | 5,123 | 5,382 |
| Warren County | 95 | -4.82% | 16,010 | 16,821 |
| Henderson County | 96 | -5.16% | 6,008 | 6,335 |
| Edwards County | 97 | -5.32% | 5,878 | 6,208 |
| Mason County | 98 | -5.44% | 12,347 | 13,058 |
| Pulaski County | 99 | -5.58% | 4,872 | 5,160 |
| Scott County | 100 | -5.91% | 4,649 | 4,941 |
| Gallatin County | 101 | -8.47% | 4,517 | 4,935 |
| Alexander County | 102 | -11.99% | 4,549 | 5,169 |