Ranking of Illinois Counties By Population Aged 25 years and above with an Educational attainment of High School Graduate or Equivalent in 2021 (ACS-5Yrs)
Updated on September 3, 2025.
Based on the US Census ACS-5Yrs estimates, in 2021, the population of Illinois (aged 25 years and above) who had an educational attainment of High School Graduate or Equivalent was 2,226,182. Among all Illinois counties, Cook County had the highest population (aged 25 years and above) with an educational attainment of High School Graduate or Equivalent (820,019), followed by Will County (119,617), and DuPage County (116,233).
The chart below shows the top 10 Illinois counties, and the table below shows the ranking of all Illinois counties.
You can see similar information for other educational attainments.
You can also see similar information for other states and for the United States.
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Related Topics: Illinois ACS-5Yrs Estimates, 2021 Topic List.
Data Source: US Census - ACS 5-Year Estimates.
Ranking of Illinois Counties By Population (Aged 25yrs+) with an Educational Attainment of High School Graduate or Equivalent in 2021
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| Rank | County | Number of People |
|---|---|---|
| 1 | Cook County | 820019 |
| 2 | Will County | 119617 |
| 3 | DuPage County | 116233 |
| 4 | Lake County | 94568 |
| 5 | Kane County | 76989 |
| 6 | Winnebago County | 60897 |
| 7 | McHenry County | 55145 |
| 8 | Madison County | 54017 |
| 9 | St. Clair County | 48222 |
| 10 | Sangamon County | 37873 |
| 11 | Peoria County | 33607 |
| 12 | Rock Island County | 29460 |
| 13 | Tazewell County | 28037 |
| 14 | LaSalle County | 27529 |
| 15 | Champaign County | 25720 |
| 16 | Macon County | 25424 |
| 17 | Kankakee County | 24927 |
| 18 | McLean County | 24299 |
| 19 | Vermilion County | 21002 |
| 20 | Kendall County | 20500 |
| 21 | Adams County | 16058 |
| 22 | DeKalb County | 15101 |
| 23 | Whiteside County | 14889 |
| 24 | Williamson County | 14301 |
| 25 | Macoupin County | 12968 |
| 26 | Knox County | 12274 |
| 27 | Ogle County | 12261 |
| 28 | Henry County | 12017 |
| 29 | Boone County | 11504 |
| 30 | Grundy County | 11068 |
| 31 | Stephenson County | 10676 |
| 32 | Livingston County | 10598 |
| 33 | Christian County | 10141 |
| 34 | Coles County | 9852 |
| 35 | Marion County | 9155 |
| 36 | Fulton County | 9143 |
| 37 | Morgan County | 8991 |
| 38 | Franklin County | 8800 |
| 39 | Lee County | 8696 |
| 40 | Clinton County | 8620 |
| 41 | Randolph County | 8519 |
| 42 | Bureau County | 8420 |
| 43 | Jefferson County | 8299 |
| 44 | Montgomery County | 8255 |
| 45 | Effingham County | 7783 |
| 46 | Iroquois County | 7444 |
| 47 | Jackson County | 7409 |
| 48 | Woodford County | 7280 |
| 49 | Logan County | 7037 |
| 50 | Shelby County | 6478 |
| 51 | Monroe County | 6299 |
| 52 | Fayette County | 6259 |
| 53 | Jo Daviess County | 5897 |
| 54 | Perry County | 5654 |
| 55 | Jersey County | 5596 |
| 56 | McDonough County | 5454 |
| 57 | Saline County | 5006 |
| 58 | Edgar County | 4796 |
| 59 | De Witt County | 4709 |
| 60 | Douglas County | 4501 |
| 61 | Hancock County | 4415 |
| 62 | Union County | 4382 |
| 63 | Mercer County | 4332 |
| 64 | Pike County | 4290 |
| 65 | Lawrence County | 4137 |
| 66 | Carroll County | 4128 |
| 67 | Clark County | 4057 |
| 68 | Crawford County | 3985 |
| 69 | Wayne County | 3967 |
| 70 | Bond County | 3916 |
| 71 | Mason County | 3914 |
| 72 | Greene County | 3838 |
| 73 | Piatt County | 3764 |
| 74 | Warren County | 3719 |
| 75 | Cass County | 3660 |
| 76 | Clay County | 3647 |
| 77 | Massac County | 3552 |
| 78 | Richland County | 3434 |
| 79 | White County | 3407 |
| 80 | Marshall County | 3365 |
| 81 | Ford County | 3328 |
| 82 | Washington County | 3307 |
| 83 | Moultrie County | 3252 |
| 84 | Johnson County | 3148 |
| 85 | Menard County | 2930 |
| 86 | Cumberland County | 2890 |
| 87 | Wabash County | 2693 |
| 88 | Jasper County | 2452 |
| 89 | Henderson County | 2085 |
| 90 | Schuyler County | 2052 |
| 91 | Hamilton County | 1847 |
| 92 | Brown County | 1770 |
| 93 | Putnam County | 1632 |
| 94 | Scott County | 1556 |
| 95 | Edwards County | 1520 |
| 96 | Stark County | 1515 |
| 97 | Pulaski County | 1507 |
| 98 | Gallatin County | 1447 |
| 99 | Alexander County | 1441 |
| 100 | Calhoun County | 1352 |
| 101 | Pope County | 1254 |
| 102 | Hardin County | 1002 |