Ranking of Illinois Counties By Population in 2015
Updated on January 28, 2024.
Based on the US Census Vintage data estimates, in 2015, the Population for Illinois was 12.86M. Among all Illinois counties, Cook County had the highest population (5.24M), followed by DuPage County (933.67K), and Lake County (704.69K).
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), 2015 Census.
See this for other years:
Ranking of Illinois Counties By Population in 2015
Rank | County | Population |
|---|---|---|
| 1 | Cook County | 5,243,371 |
| 2 | DuPage County | 933,669 |
| 3 | Lake County | 704,687 |
| 4 | Will County | 685,825 |
| 5 | Kane County | 528,562 |
| 6 | McHenry County | 307,595 |
| 7 | Winnebago County | 287,237 |
| 8 | Madison County | 266,112 |
| 9 | St. Clair County | 265,008 |
| 10 | Champaign County | 209,534 |
| 11 | Sangamon County | 198,973 |
| 12 | Peoria County | 186,552 |
| 13 | McLean County | 173,222 |
| 14 | Rock Island County | 146,161 |
| 15 | Tazewell County | 134,350 |
| 16 | Kendall County | 122,892 |
| 17 | Kankakee County | 111,786 |
| 18 | LaSalle County | 111,015 |
| 19 | Macon County | 107,398 |
| 20 | DeKalb County | 104,238 |
| 21 | Vermilion County | 79,209 |
| 22 | Williamson County | 67,457 |
| 23 | Adams County | 66,850 |
| 24 | Jackson County | 59,249 |
| 25 | Whiteside County | 56,943 |
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