
The number of state residents under 20 fell 6.8% from 2020 to 2025.
By Bryce Hill | Illinois Policy Institute
A sharp decline in young people in Illinois and other newly released age data should concern state leaders and spur work on solutions.
From 2020 to 2025, Illinois’ population of residents under 20 fell by 6.8%, more than three times faster than the national average of 2%, according to the U.S. Census Bureau.

The number of state residents under 20 fell by over 36,000 last year and nearly 214,000 since 2020.
Meanwhile, the population of older Illinoisans saw a large increase in that time. The number of those 60 and older rose by more than 46,387 last year and more than 240,000 since 2020.
Both nationally and in Illinois the number of residents in their 50s declined as the large Baby Boomer generation has aged. The population of those 60 and over increased by 11% nationally and 8.2% in Illinois from 2020 to 2025.
Other younger age groups also are growing far faster across the nation than in Illinois. From 2020 to 2025:
- The population of those in their 20s grew by 4.3% nationally but only 1% in Illinois.
- The number of 30-somethings grew by 4.7% in the U.S. but a mere 0.5% in Illinois.
- The population in their 40s grew by 5.5% nationally but only 1.2% in Illinois.
The state’s median age has increased to 39.7, slightly above the national median of 39.4.
While the population changes by age trends in the U.S. and Illinois are similar in directionality, the state is seeing more substantial shifts in its age profile. These differences are likely due to outmigration trends in Illinois, as a net number of retirees and younger families are moving out of the state. Thus while Illinois’ median age might closely track the national figure today, the state’s population changes are much more concerning than what the nation as a whole is experiencing.
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