Ranking of Illinois Counties By Percentage of Population Aged 25 years and above with an Educational attainment of Less than High School Diploma in 2021 (ACS-5Yrs)
Updated on September 3, 2025.
Based on the US Census ACS-5Yrs estimates, in 2021, the percentage of the population of Illinois (aged 25 years and above) who had an educational attainment of Less than High School Diploma was 10.10%. Among all Illinois counties, Brown County had the highest percentage of its population (aged 25 years and above) with an educational attainment of Less than High School Diploma (19.31%), followed by Johnson County (16.92%), and Perry County (16.38%).
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.
You may also be interested in:
Related Topics: Illinois ACS-5Yrs Estimates, 2021 Topic List.
Data Source: US Census - ACS 5-Year Estimates.
Ranking of Illinois Counties By Percentage of Population (Aged 25yrs+) with an Educational Attainment of Less than High School Diploma in 2021
Items per page:
25
0 of 0
| Rank | County | Percentage of Population (Aged 25yrs+) (%) |
|---|---|---|
| 1 | Brown County | 19.31 |
| 2 | Johnson County | 16.92 |
| 3 | Perry County | 16.38 |
| 4 | Douglas County | 16.12 |
| 5 | Lawrence County | 15.64 |
| 6 | Hardin County | 15.19 |
| 7 | Cass County | 15.06 |
| 8 | Randolph County | 14.92 |
| 9 | Kane County | 13.97 |
| 10 | Alexander County | 13.80 |
| 11 | Crawford County | 13.69 |
| 12 | Fayette County | 13.57 |
| 13 | Moultrie County | 13.45 |
| 14 | Boone County | 12.92 |
| 15 | Massac County | 12.69 |
| 16 | Wayne County | 12.61 |
| 17 | Montgomery County | 12.15 |
| 17 | Saline County | 12.15 |
| 18 | Warren County | 12.12 |
| 19 | Carroll County | 12.08 |
| 20 | Cook County | 12.03 |
| 21 | Edgar County | 12.00 |
| 22 | Gallatin County | 11.97 |
| 23 | Hamilton County | 11.84 |
| 24 | Winnebago County | 11.82 |
| 25 | Clay County | 11.62 |
| 26 | Iroquois County | 11.56 |
| 27 | Bond County | 11.24 |
| 28 | Knox County | 11.06 |
| 29 | Marion County | 11.01 |
| 30 | Rock Island County | 10.98 |
| 31 | Pope County | 10.88 |
| 32 | Union County | 10.77 |
| 33 | Pulaski County | 10.71 |
| 34 | Morgan County | 10.60 |
| 35 | Christian County | 10.59 |
| 36 | Fulton County | 10.49 |
| 37 | Kankakee County | 10.46 |
| 38 | Franklin County | 10.45 |
| 39 | Stark County | 10.42 |
| 40 | Lee County | 10.38 |
| 41 | White County | 10.31 |
| 42 | Jefferson County | 10.11 |
| 43 | Livingston County | 9.86 |
| 44 | Vermilion County | 9.77 |
| 45 | Logan County | 9.65 |
| 46 | LaSalle County | 9.45 |
| 47 | Bureau County | 9.40 |
| 48 | Mason County | 9.36 |
| 49 | Greene County | 9.34 |
| 50 | Lake County | 9.19 |
| 51 | Ogle County | 9.05 |
| 52 | Macoupin County | 8.91 |
| 53 | Pike County | 8.86 |
| 54 | Clinton County | 8.70 |
| 55 | Whiteside County | 8.65 |
| 56 | Will County | 8.52 |
| 57 | Jackson County | 8.37 |
| 58 | Ford County | 8.25 |
| 58 | Macon County | 8.25 |
| 59 | Wabash County | 8.12 |
| 60 | Stephenson County | 8.10 |
| 61 | Coles County | 8.07 |
| 62 | Jasper County | 7.97 |
| 63 | Washington County | 7.87 |
| 64 | Edwards County | 7.86 |
| 65 | Peoria County | 7.82 |
| 66 | Jo Daviess County | 7.76 |
| 67 | St. Clair County | 7.73 |
| 68 | Henry County | 7.72 |
| 69 | Richland County | 7.67 |
| 70 | Jersey County | 7.59 |
| 70 | Schuyler County | 7.59 |
| 71 | Adams County | 7.56 |
| 72 | Marshall County | 7.55 |
| 73 | Henderson County | 7.54 |
| 74 | Mercer County | 7.48 |
| 75 | DeKalb County | 7.37 |
| 76 | Williamson County | 7.31 |
| 77 | Calhoun County | 7.24 |
| 78 | Sangamon County | 7.23 |
| 79 | Cumberland County | 7.08 |
| 80 | Madison County | 7.00 |
| 81 | Clark County | 6.96 |
| 82 | De Witt County | 6.88 |
| 82 | Effingham County | 6.88 |
| 83 | Shelby County | 6.84 |
| 84 | Tazewell County | 6.78 |
| 85 | Putnam County | 6.69 |
| 86 | Hancock County | 6.59 |
| 87 | DuPage County | 6.51 |
| 88 | McHenry County | 6.47 |
| 89 | Grundy County | 6.39 |
| 90 | Kendall County | 6.38 |
| 91 | Piatt County | 6.30 |
| 92 | Scott County | 6.00 |
| 93 | Woodford County | 5.72 |
| 94 | Champaign County | 5.23 |
| 95 | McDonough County | 4.95 |
| 96 | Monroe County | 4.69 |
| 97 | Menard County | 4.28 |
| 98 | McLean County | 4.01 |