Ranking of Illinois Counties By Population in 2021
Updated on June 18, 2025.
Based on the US Census Vintage data estimates, in 2021, the Population for Illinois was 12.70M. Among all Illinois counties, Cook County had the highest population (5.19M), followed by DuPage County (927.15K), and Lake County (712.73K).
The chart below shows the top 10 counties, and the table below shows the ranking of all Illinois counties.
You can see similar ranking information for related topics, and for other states. You can also see the ranking of all counties in the United States.
Related Topics: Illinois Census Vintage Data Topic List.
Data Source: US Census Bureau (Vintage), 2021 Census.
See this for other years:
Ranking of Illinois Counties By Population in 2021
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| Rank | County | Population |
|---|---|---|
| 1 | Cook County | 5185134 |
| 2 | DuPage County | 927145 |
| 3 | Lake County | 712733 |
| 4 | Will County | 699327 |
| 5 | Kane County | 516564 |
| 6 | McHenry County | 311669 |
| 7 | Winnebago County | 283413 |
| 8 | Madison County | 265001 |
| 9 | St. Clair County | 255210 |
| 10 | Champaign County | 207232 |
| 11 | Sangamon County | 195468 |
| 12 | Peoria County | 179847 |
| 13 | McLean County | 171411 |
| 14 | Rock Island County | 142943 |
| 15 | Kendall County | 135023 |
| 16 | Tazewell County | 130640 |
| 17 | LaSalle County | 109166 |
| 18 | Kankakee County | 106757 |
| 19 | Macon County | 102619 |
| 20 | DeKalb County | 100584 |
| 21 | Vermilion County | 73175 |
| 22 | Williamson County | 66895 |
| 23 | Adams County | 65077 |
| 24 | Whiteside County | 55320 |
| 25 | Boone County | 53173 |
| 26 | Jackson County | 52986 |
| 27 | Grundy County | 52984 |
| 28 | Ogle County | 51540 |
| 29 | Knox County | 49333 |
| 30 | Henry County | 48929 |
| 31 | Coles County | 47136 |
| 32 | Macoupin County | 44563 |
| 33 | Stephenson County | 44130 |
| 34 | Woodford County | 38220 |
| 35 | Franklin County | 37484 |
| 36 | Marion County | 37390 |
| 37 | Jefferson County | 36899 |
| 38 | Clinton County | 36898 |
| 39 | Livingston County | 35799 |
| 40 | Monroe County | 35007 |
| 41 | Effingham County | 34514 |
| 42 | Lee County | 34202 |
| 43 | Christian County | 33731 |
| 44 | Fulton County | 33344 |
| 45 | Morgan County | 33289 |
| 46 | Bureau County | 32999 |
| 47 | Randolph County | 30207 |
| 48 | Montgomery County | 28128 |
| 49 | Logan County | 27978 |
| 50 | McDonough County | 26906 |
| 51 | Iroquois County | 26761 |
| 52 | Saline County | 23368 |
| 53 | Jo Daviess County | 22016 |
| 54 | Fayette County | 21438 |
| 55 | Jersey County | 21350 |
| 56 | Perry County | 21027 |
| 57 | Shelby County | 20853 |
| 58 | Douglas County | 19714 |
| 59 | Crawford County | 18673 |
| 60 | Hancock County | 17395 |
| 61 | Union County | 17035 |
| 62 | Bond County | 16797 |
| 63 | Piatt County | 16764 |
| 64 | Edgar County | 16601 |
| 65 | Warren County | 16595 |
| 66 | Wayne County | 15995 |
| 67 | Richland County | 15784 |
| 68 | Carroll County | 15712 |
| 69 | Mercer County | 15583 |
| 70 | De Witt County | 15410 |
| 71 | Clark County | 15375 |
| 72 | Lawrence County | 15246 |
| 73 | Pike County | 14621 |
| 74 | Moultrie County | 14573 |
| 75 | Massac County | 13953 |
| 76 | White County | 13767 |
| 77 | Washington County | 13651 |
| 78 | Johnson County | 13481 |
| 79 | Ford County | 13480 |
| 80 | Clay County | 13166 |
| 81 | Mason County | 12826 |
| 82 | Cass County | 12778 |
| 83 | Menard County | 12170 |
| 84 | Greene County | 11848 |
| 85 | Marshall County | 11665 |
| 86 | Wabash County | 11209 |
| 87 | Cumberland County | 10358 |
| 88 | Jasper County | 9210 |
| 89 | Hamilton County | 7908 |
| 90 | Schuyler County | 6835 |
| 91 | Brown County | 6444 |
| 92 | Henderson County | 6309 |
| 93 | Edwards County | 6087 |
| 94 | Putnam County | 5589 |
| 95 | Stark County | 5291 |
| 96 | Pulaski County | 5093 |
| 97 | Alexander County | 5028 |
| 98 | Scott County | 4984 |
| 99 | Gallatin County | 4908 |
| 100 | Calhoun County | 4392 |
| 101 | Pope County | 3763 |
| 102 | Hardin County | 3640 |