Illinois Counties by Population (2026)
by Kristen Carney
Updated: February 9, 2026
The most populous counties in Illinois are Cook County with 5,182,090, DuPage County at 930,024, Lake County with 714,223, Will County at 701,462, and Kane County with 517,255. You can get the most current Census population data for all 102 Illinois counties, sorted from the most populous counties in Illinois to the least, according to the 2024 American Community Survey.
Sure, you can copy this list right into your favorite spreadsheet tool. Or save yourself formatting headaches and grab the latest Illinois counties population data as a ready-to-use Excel™ file below. It's time to stop searching and start digging into data!
| Rank | County | Population |
|---|---|---|
| 1 | Cook County | 5,182,090 |
| 2 | DuPage County | 930,024 |
| 3 | Lake County | 714,223 |
| 4 | Will County | 701,462 |
| 5 | Kane County | 517,255 |
| 6 | McHenry County | 312,591 |
| 7 | Winnebago County | 283,292 |
| 8 | Madison County | 264,238 |
| 9 | St. Clair County | 253,694 |
| 10 | Champaign County | 208,741 |
| 11 | Sangamon County | 194,947 |
| 12 | Peoria County | 179,645 |
| 13 | McLean County | 171,556 |
| 14 | Rock Island County | 142,757 |
| 15 | Kendall County | 137,675 |
| 16 | Tazewell County | 130,290 |
| 17 | LaSalle County | 108,714 |
| 18 | Kankakee County | 106,635 |
| 19 | Macon County | 101,849 |
| 20 | DeKalb County | 100,703 |
| 21 | Vermilion County | 72,386 |
| 22 | Williamson County | 66,876 |
| 23 | Adams County | 64,754 |
| 24 | Whiteside County | 54,947 |
| 25 | Boone County | 53,230 |
| 26 | Grundy County | 53,219 |
| 27 | Jackson County | 53,064 |
| 28 | Ogle County | 51,495 |
| 29 | Knox County | 49,046 |
| 30 | Henry County | 48,643 |
| 31 | Coles County | 46,777 |
| 32 | Macoupin County | 44,350 |
| 33 | Stephenson County | 43,768 |
| 34 | Woodford County | 38,312 |
| 35 | Franklin County | 37,323 |
| 36 | Marion County | 37,000 |
| 37 | Clinton County | 36,954 |
| 38 | Jefferson County | 36,550 |
| 39 | Livingston County | 35,565 |
| 40 | Monroe County | 35,036 |
| 41 | Effingham County | 34,522 |
| 42 | Lee County | 33,869 |
| 43 | Christian County | 33,538 |
| 44 | Morgan County | 33,021 |
| 45 | Fulton County | 33,020 |
| 46 | Bureau County | 32,866 |
| 47 | Randolph County | 30,058 |
| 48 | Montgomery County | 27,942 |
| 49 | Logan County | 27,713 |
| 50 | McDonough County | 26,920 |
| 51 | Iroquois County | 26,449 |
| 52 | Saline County | 23,213 |
| 53 | Jo Daviess County | 21,851 |
| 54 | Fayette County | 21,315 |
| 55 | Jersey County | 21,274 |
| 56 | Shelby County | 20,720 |
| 57 | Perry County | 20,639 |
| 58 | Douglas County | 19,751 |
| 59 | Crawford County | 18,511 |
| 60 | Hancock County | 17,281 |
| 61 | Union County | 16,997 |
| 62 | Bond County | 16,716 |
| 63 | Piatt County | 16,695 |
| 64 | Edgar County | 16,535 |
| 65 | Warren County | 16,447 |
| 66 | Wayne County | 15,973 |
| 67 | Richland County | 15,598 |
| 68 | Carroll County | 15,576 |
| 69 | Mercer County | 15,495 |
| 70 | De Witt County | 15,373 |
| 71 | Clark County | 15,266 |
| 72 | Lawrence County | 15,031 |
| 73 | Pike County | 14,469 |
| 74 | Moultrie County | 14,424 |
| 75 | Massac County | 13,865 |
| 76 | Washington County | 13,627 |
| 77 | White County | 13,619 |
| 78 | Ford County | 13,406 |
| 79 | Johnson County | 13,376 |
| 80 | Clay County | 13,052 |
| 81 | Cass County | 12,784 |
| 82 | Mason County | 12,745 |
| 83 | Menard County | 12,095 |
| 84 | Greene County | 11,683 |
| 85 | Marshall County | 11,647 |
| 86 | Wabash County | 11,119 |
| 87 | Cumberland County | 10,334 |
| 88 | Jasper County | 9,180 |
| 89 | Hamilton County | 7,916 |
| 90 | Schuyler County | 6,787 |
| 91 | Brown County | 6,322 |
| 92 | Henderson County | 6,193 |
| 93 | Edwards County | 6,075 |
| 94 | Putnam County | 5,601 |
| 95 | Stark County | 5,308 |
| 96 | Pulaski County | 5,015 |
| 97 | Scott County | 4,937 |
| 98 | Alexander County | 4,875 |
| 99 | Gallatin County | 4,819 |
| 100 | Calhoun County | 4,330 |
| 101 | Pope County | 3,739 |
| 102 | Hardin County | 3,605 |
|
United States Census Bureau. B01001 SEX BY AGE, 2024 American Community Survey 5-Year Estimates. U.S. Census Bureau, American Community Survey Office. Web. January 29, 2026. http://www.census.gov/. |
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