Illinois population: 12.7 million people, and only 18 counties still growing
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Illinois had an estimated 12,719,141 residents in 2025, according to the Census Bureau, down about 93,000 from the 12,812,508 counted in the 2020 census. It is the sixth most populous state, behind Pennsylvania and ahead of Ohio.
Illinois is one of only three states with fewer residents in the 2020-2024 American Community Survey than in the 2010 census, along with West Virginia and Mississippi. The state peaked in the 2010 census at 12,830,632 and has drifted down slowly since, a loss of less than 1 percent in 15 years.
| Year | Illinois population |
|---|---|
| 1990 | 11,430,602 |
| 2000 | 12,419,293 |
| 2010 | 12,830,632 |
| 2020 | 12,812,508 |
| 2025 (estimate) | 12,719,141 |
Where the losses and gains are
Only 18 of the state's 102 counties grew between 2020 and 2025. Cook County, home to Chicago and about 41 percent of the state's people, fell 1.5 percent to 5,194,625. Most of the collar counties around it grew slightly: Will County rose 2.3 percent to 712,253, Kane 1.8 percent, Lake 0.7 percent, and DuPage 0.2 percent. McHenry grew 2.4 percent.
The fastest-growing county by far was Kendall County, southwest of Chicago, up 10.3 percent to 145,470. The steepest losses were in the rural far south. Alexander County, at the state's southern tip, fell 12.8 percent to 4,570 residents, and Pulaski County, next to it, fell 7.2 percent.
Chicago had an estimated 2,731,585 people in 2025, down 0.5 percent from 2020. The next largest cities were all suburbs or regional hubs:
| City | 2025 estimate | Change since 2020 |
|---|---|---|
| Chicago | 2,731,585 | -0.5% |
| Aurora | 181,505 | +0.5% |
| Naperville | 153,114 | +2.4% |
| Joliet | 152,241 | +1.2% |
| Rockford | 147,384 | -0.9% |
| Elgin | 115,476 | +0.6% |
| Springfield | 112,989 | -1.2% |
| Peoria | 110,920 | -2.0% |
Who lives in Illinois
In the 2020 to 2024 American Community Survey, Illinois was 58.1 percent non-Hispanic white, 18.8 percent Hispanic, 13.3 percent Black, and 5.9 percent Asian. The Hispanic share has more than doubled since 1990, when it was 7.7 percent, and 14.7 percent of residents were born in another country.
The median household income was $83,390, and the poverty rate was 11.8 percent. The median age rose from 32.9 in 1990 to 39.0, and its under-20 population is shrinking, which we covered in Illinois' shrinking under-20 population.
Every county and city in the state has its own page, starting from the Illinois state page.
Sources
Population figures for 1990, 2000, 2010, and 2020 are from the decennial census. The 2025 figures are from the Census Bureau's Vintage 2025 Population Estimates, with the state total summed from county estimates by CensusEasy. The comparison of states that lost population uses the 2010 census and the 2020-2024 American Community Survey 5-year estimates, which are also the source for the race, income, poverty, age, and foreign-born figures for recent years. 1990 figures are from the 1990 census.
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What is the population of Illinois?
Illinois had an estimated 12,719,141 residents in 2025, according to the Census Bureau's Vintage 2025 estimates. The 2020 census counted 12,812,508, and the state's peak was 12,830,632 in the 2010 census. It is the sixth most populous state.
Is Illinois losing population?
Slowly. Illinois lost about 93,000 people from 2020 to 2025, and it was one of three states, with West Virginia and Mississippi, with fewer residents in the 2020-2024 American Community Survey than in the 2010 census. Only 18 of its 102 counties grew since 2020.
What are the largest cities in Illinois?
Chicago is by far the largest at 2,731,585 in 2025. Next are Aurora at 181,505, Naperville at 153,114, Joliet at 152,241, and Rockford at 147,384. Springfield, the state capital, has 112,989 residents.
