Illinois lost population since 2020, but these 15 counties gained new residents
While Illinois lost population as a whole in recent years, 15 of its 102 counties gained residents from 2020 to 2024, according to data from the U.S. Census Bureau.
The bureau’s estimates of the resident population change from April 1, 2020, to July 1, 2024, released in March, show Kendall, Champaign, Grundy, McHenry and Will counties gained the greatest percentage of residents, though the change wasn’t stark for most.
Although none of the metro-east’s counties cracked the top five, Clinton and Monroe counties did see modest population gains, with Clinton adding 174 residents and Monroe adding 16. Brown, DeKalb, Kane, Lake, DuPage, McLean, Douglas and Putnam counties also saw net population gains from 2020 to 2024.
Four of the top five counties for growth are in northeastern Illinois, but central Illinois’ Champaign County saw the second-greatest percentage of population growth. The city of Champaign, located within the county, was recently named among the “Top 100 Best Places to Live in the US in 2025” by online publication Livability.
From 2020 to 2024 overall, Illinois lost 88,930 residents statewide, but the Land of Lincoln gained in 2023 and 2024. NBC Chicago reported in December that officials credited a “significant increase” in net international migration to Illinois for the gains between 2023 and 2024.
Illinois has a slightly higher portion of residents who were not born in the U.S., at 15%, compared to the national average of 14.3%, according to 2023 Census Bureau data.
Those who moved from Illinois to other states in 2023 most often moved to Indiana, Florida, Wisconsin, Texas and California, Fox 2 reported in October.
Here’s what to know about the Illinois counties with the greatest percentage gain of residents, as well as population trends in the metro-east.
Top 5 Illinois counties for population growth
1. Kendall County
Kendall County saw an 8.18% increase in residents from 2020 to 2024, by far the greatest growth of any Illinois county. Kendall is in the Chicago metropolitan area, and gained 10,820 residents over the four-year period.
What to know about Kendall County, from the Census Bureau:
Median household income: $110,474
Poverty rate: 5.1%
Median monthly housing costs with a mortgage: $2,229
Median gross monthly rent: $1,763
2. Champaign County
Champaign County gained 6,122 residents from 2020 to 2024, representing a 2.97% increase in population.
Median household income: $63,091
Poverty rate: 16.2%
Median monthly housing costs with a mortgage: $1,609
Median gross monthly rent: $1,018
3. Grundy County
Grundy County saw a 2.47% increase in population, with 1,300 new residents. Grundy borders Kendall County to the south, and encompasses rural and urban areas, according to its chamber of commerce.
Median household income: $93,060
Poverty rate: 6.8%
Median monthly housing costs with a mortgage: $1,946
Median gross monthly rent: $1,137
4. McHenry County
McHenry County saw a 1.93% increase in population, with 5,986 new residents. The county borders Wisconsin and is about 64 miles from Chicago by car.
Median household income: $102,836
Poverty rate: 6.3%
Median monthly housing costs with a mortgage: $2,092
Median gross monthly rent: $1,358
5. Will County
Will County saw a 1.68% increase in population, with 11,674 new residents. Nestled between Cook, Grundy and Kendall counties, Will County is home to parts of Aurora and Naperville. Along with Champaign, Naperville also made the Livability list for the 100 best places to live in the U.S.
Median household income: $107,799
Poverty rate: 7.2%
Median monthly housing costs with a mortgage: $2,201
Median gross monthly rent: $1,413
How is the metro-east doing?
Although St. Clair County didn’t top the list for the counties with the greatest percentage population decrease, the county lost the second greatest number of residents at 5,921. Cook County lost the greatest number of residents, at 84,455.
Calhoun: Lost 179 residents, or 4.07% of population
St. Clair: Lost 5,921 residents or 2.3% of population
Macoupin: Lost 1,029 residents, or 2.29% of population
Bond: Lost 280 residents, or 1.66% of population
Jersey: Lost 342 residents, or 1.59% of population
Madison: Lost 2,732 residents or 1.03% of population
Monroe: Gained 16 residents, or 0.05% of population
Clinton: Gained 174 residents, or 0.47% of population
Note: An AI tool assisted with organizing the data for this story. A Belleville News-Democrat journalist reviewed the data and wrote the story. Percentages of population gain and decline are rounded to the nearest hundredth.
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