Median Age in St. Clair County, IL
ACS 2024 5-Year Estimates
39.9 years
Rank #2,142/3,222 · #82 in IL
34th
St. Clair 39.9 years
IL 39.0 years +2.3%
US 38.9 years +2.6%
Median Age Trend
Rankings →Percentile Rank Over Time
Year-over-Year Age Change
National Distribution
How St. Clair County's median age of 39.9 years compares to all 3,222 U.S. counties. Values range from 21.4 years to 86.2 years.
Distribution of Median Age Across All Counties
Ranking Context
Counties ranked closest to St. Clair County for median age.
Nearby Rankings
Full ranking →| #2,139 | Jeff Davis County, GA | 39.9 years |
| #2,140 | Madison County, GA | 39.9 years |
| #2,141 | Pike County, GA | 39.9 years |
| #2,142 | St. Clair County, IL | 39.9 years |
| #2,143 | Benton County, IN | 39.9 years |
| #2,144 | Clark County, IN | 39.9 years |
| #2,145 | Marion County, IA | 39.9 years |
About Median Age
St. Clair County, Illinois has a median age of 39.9 years, ranking #2,142 of 3,222 counties nationwide — 2.6% above the national value of 38.9 years. Within Illinois, it ranks #82 of 102. This places it in the 34th percentile nationally.
The median age of the total population. Source: U.S. Census Bureau, American Community Survey 2024 5-Year Estimates. All values are estimates derived from survey samples and are subject to margin of error. For more information, see our methodology.