Illinois Counties by Population (2026)
2026 Pop.
500K
1M
1.5M
2M
2.5M
3M
3.5M
4M
4.5M
5M
Top 5 Most Populous Counties
5,200,459
935,945
720,188
715,526
528,084
| County | 2026 Pop. ↓ | Area (mi²) | Density (/mi²) | Change (2020) |
|---|---|---|---|---|
| Cook County | 5,200,459 | 945 | 5,503 | -1.2% |
| DuPage County | 935,945 | 328 | 2,853 | 0.48% |
| Lake County | 720,188 | 444 | 1,622 | 0.95% |
| Will County | 715,526 | 836 | 856 | 2.67% |
| Kane County | 528,084 | 519 | 1,018 | 2.27% |
| McHenry County | 319,772 | 603 | 530 | 3.16% |
| Winnebago County | 284,383 | 513 | 554 | -0.2% |
| Madison County | 262,903 | 716 | 367 | -1.07% |
| St. Clair County | 250,041 | 658 | 380 | -2.73% |
| Champaign County | 210,766 | 1K | 212 | 2.2% |
| Sangamon County | 194,304 | 868 | 224 | -0.97% |
| Peoria County | 178,565 | 619 | 288 | -1.62% |
| McLean County | 171,326 | 1.2K | 145 | 0.07% |
| Kendall County | 147,815 | 320 | 462 | 11.67% |
| Rock Island County | 142,147 | 427 | 333 | -1.53% |
| Tazewell County | 130,116 | 646 | 201 | -0.9% |
| LaSalle County | 107,671 | 1.1K | 95 | -1.59% |
| Kankakee County | 105,236 | 676 | 156 | -2.02% |
| DeKalb County | 103,049 | 631 | 163 | 2.67% |
| Macon County | 98,651 | 581 | 170 | -4.92% |
| Vermilion County | 71,062 | 898 | 79 | -3.98% |
| Williamson County | 67,376 | 420 | 160 | 0.37% |
| Adams County | 64,318 | 855 | 75 | -2.01% |
| Grundy County | 54,383 | 418 | 130 | 3.51% |
| Whiteside County | 53,819 | 684 | 79 | -3.12% |
| Boone County | 53,610 | 281 | 191 | 0.5% |
| Jackson County | 52,320 | 584 | 90 | -1.82% |
| Ogle County | 51,524 | 759 | 68 | -0.47% |
| Henry County | 47,997 | 823 | 58 | -2.39% |
| Knox County | 47,570 | 716 | 66 | -4.5% |
| Coles County | 46,641 | 508 | 92 | -0.95% |
| Macoupin County | 43,579 | 863 | 50 | -3% |
| Stephenson County | 43,018 | 564 | 76 | -3.48% |
| Woodford County | 38,024 | 528 | 72 | -0.99% |
| Clinton County | 37,168 | 474 | 78 | 0.69% |
| Franklin County | 36,878 | 409 | 90 | -2.16% |
| Marion County | 36,263 | 573 | 63 | -3.7% |
| Jefferson County | 36,182 | 571 | 63 | -2.21% |
| Livingston County | 34,930 | 1K | 33 | -2.45% |
| Monroe County | 34,575 | 385 | 90 | -1.1% |
| Effingham County | 34,497 | 479 | 72 | -0.57% |
| Christian County | 33,444 | 709 | 47 | -1.52% |
| Fulton County | 32,995 | 866 | 38 | -1.69% |
| Lee County | 32,977 | 725 | 45 | -3.19% |
| Bureau County | 32,501 | 869 | 37 | -2.15% |
| Morgan County | 32,391 | 569 | 57 | -3.28% |
| Randolph County | 29,972 | 575 | 52 | -0.4% |
| Montgomery County | 28,315 | 704 | 40 | 0.25% |
| Logan County | 27,145 | 618 | 44 | -2.68% |
| Iroquois County | 26,078 | 1.1K | 23 | -3.3% |
| McDonough County | 25,717 | 589 | 44 | -5.2% |
| Saline County | 22,714 | 380 | 60 | -4.33% |
| Jo Daviess County | 21,532 | 601 | 36 | -2.53% |
| Jersey County | 21,165 | 370 | 57 | -1.53% |
| Fayette County | 20,626 | 716 | 29 | -3.99% |
| Shelby County | 20,598 | 759 | 27 | -1.54% |
| Perry County | 19,944 | 442 | 45 | -4.5% |
| Douglas County | 19,912 | 417 | 48 | 0.7% |
| Crawford County | 18,675 | 444 | 42 | 0.24% |
| Bond County | 17,318 | 380 | 46 | 2.72% |
| Piatt County | 16,940 | 439 | 39 | 1.51% |
| Hancock County | 16,670 | 794 | 21 | -5.12% |
| Union County | 16,480 | 413 | 40 | -4.73% |
| Warren County | 16,328 | 542 | 30 | -3.02% |
| Edgar County | 16,264 | 623 | 26 | -3.23% |
| Wayne County | 15,881 | 714 | 22 | -1.62% |
| Carroll County | 15,370 | 445 | 35 | -2.01% |
| Mercer County | 15,166 | 561 | 27 | -3.01% |
| Clark County | 15,087 | 501 | 30 | -2.39% |
| Richland County | 15,070 | 360 | 42 | -4.67% |
| De Witt County | 14,992 | 398 | 38 | -2.96% |
| Moultrie County | 14,300 | 336 | 43 | -1.28% |
| Pike County | 14,176 | 831 | 17 | -3.14% |
| Lawrence County | 13,813 | 372 | 37 | -9.58% |
| Washington County | 13,549 | 563 | 24 | -1.31% |
| Massac County | 13,388 | 237 | 56 | -5.32% |
| Johnson County | 13,379 | 344 | 39 | 0.47% |
| Ford County | 13,106 | 486 | 27 | -3.05% |
| White County | 13,051 | 495 | 26 | -5.48% |
| Clay County | 12,741 | 468 | 27 | -3.99% |
| Cass County | 12,396 | 376 | 33 | -4.48% |
| Mason County | 12,333 | 539 | 23 | -5.49% |
| Menard County | 11,802 | 314 | 38 | -3.84% |
| Marshall County | 11,375 | 387 | 29 | -2.89% |
| Greene County | 11,233 | 543 | 21 | -5.8% |
| Wabash County | 10,788 | 223 | 48 | -4.69% |
| Cumberland County | 10,138 | 346 | 29 | -2.82% |
| Jasper County | 9,015 | 495 | 18 | -2.57% |
| Hamilton County | 7,857 | 435 | 18 | -1.74% |
| Schuyler County | 6,591 | 437 | 15 | -3.99% |
| Brown County | 6,364 | 306 | 21 | 2.12% |
| Henderson County | 5,937 | 379 | 16 | -6.36% |
| Edwards County | 5,809 | 222 | 26 | -6.41% |
| Putnam County | 5,621 | 160 | 35 | -0.05% |
| Stark County | 5,369 | 288 | 19 | -0.24% |
| Scott County | 4,843 | 251 | 19 | -4.48% |
| Pulaski County | 4,757 | 199 | 24 | -8.1% |
| Gallatin County | 4,549 | 323 | 14 | -7.78% |
| Alexander County | 4,529 | 235 | 19 | -12.43% |
| Calhoun County | 4,290 | 254 | 17 | -2.48% |
| Pope County | 3,627 | 369 | 9.8 | -3.41% |
| Hardin County | 3,575 | 177 | 20 | -2.16% |
Sources
- US Census State Population Estimates - Most recent state estimates from the Census Bureau's Population Estimates Program
- US Census County Population Estimates - Most recent county estimates from the Census Bureau's Population Estimates Program
- American Community Survey (2009 - 2013)
- Census QuickFacts
- Historical Populations of States and Counties (1790 - 1990)