Jefferson County, Illinois Population 2026
Updated April 2026 · US Census ACS 2023 5-Year Estimates · 38th-largest in Illinois
The population of Jefferson County, Illinois is 36,808 as of the 2023 American Community Survey, making it the 38th-largest county in Illinois. The median household income is $61,102, the median home value is $118,400, and the median age is 41.1.
The population of Jefferson County has declined 6.8% since 2010 (38,757 → 36,107), a -0.50% annualized rate.
36,808
Population
-0.50%
Annual growth
64
People / sq mi
$61,102
Median Income
$118,400
Median Home Value
Jefferson County covers 571 sq mi of land at 64.4 people per square mile.
About Jefferson County, IL
Jefferson County is a county in Illinois with a population of 36,808. It ranks #38 among counties in Illinois by population. The median age is 41.1, older than the national median. The population is 51.5% male and 48.5% female.
The median household income in Jefferson County is $61,102, below the US median of $74,580. 11.4% of residents live below the federal poverty level. Home values sit at a median of $118,400, with monthly rent averaging $862. The homeownership rate of 71.9% is higher than the national rate of 64.8%.
Educational attainment in Jefferson County reflects 18.4% of adults 25 and older holding a bachelor's degree or higher, below the national average of 34.3%. Roughly 4.8% of workers primarily work from home, below the national work-from-home rate of 14.2%. The average commute is 19.7 minutes each way.
Jefferson County Population History (2010-2024)
The county of Jefferson County had a population of 38,757 in 2010 and 36,107 in 2024, a -6.8% growth over 14 years. The peak was 38,758 in 2011. Average annual growth rate: -0.50%.
36,107
Population (2024)
38,757
Population (2010)
38,758
Peak (2011)
-0.50%
Avg Annual Growth
| Year | Population |
|---|---|
| 2010 | 38,757 |
| 2011 | 38,758 |
| 2012 | 38,672 |
| 2013 | 38,656 |
| 2014 | 38,390 |
| 2015 | 38,290 |
| 2016 | 38,236 |
| 2017 | 38,059 |
| 2018 | 37,704 |
| 2019 | 37,635 |
| 2020 | 37,000 |
| 2021 | 36,899 |
| 2022 | 36,415 |
| 2023 | 36,331 |
| 2024 | 36,107 |
Race & Ethnicity
| White | 84.9% |
| Black or African American | 6.5% |
| Asian | 0.0% |
| Hispanic or Latino (any race) | 2.2% |
| Two or More Races | 0.0% |
Age & Sex
41.1
Median Age
48.5%
Female
51.5%
Male
19.7%
Age 65+
Age Distribution
Children (under 15): 18.6% · Seniors (65+): 19.7%
Income & Poverty
| Median household income | $61,102$-20,600 vs state |
| Mean household income | $77,553 |
| Per-capita income | $31,541 |
| Poverty rate | 11.4%+3.2% vs state |
| Unemployment rate | 3.8% |
| Employment-to-population | 54.5% |
Top Industries by Employment
The largest employment sector in Jefferson County is professional & business services, accounting for 24.3% of workers.
How residents commute
0.3%
Drive alone
1.1%
Carpool
82.3%
Public transit
4.8%
Work from home
19.7 min
Avg commute
Housing
$118,400$-132,100 vs state
Median home value
$862
Median rent
71.9%
Homeownership rate
16,650
Total housing units
88.9%
Occupied
11.1%
Vacant
28.1%
Renter-occupied
Social & access
92.5%
With health insurance
91.8%
With broadband internet
18.4%
Foreign-born
8.2%
Veterans (18+)
18.3%
With a disability
96.1%
Speak language other than English at home
Education
91.4%
High School+
18.4%
Bachelor's+
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Part of Illinois
Metro areas in Illinois
County rankings
Frequently Asked Questions
Jefferson County, Illinois has a population of 36,808 according to the US Census Bureau's 2023 American Community Survey 5-year estimates, making it the 38th-largest county in Illinois. Population density is 64 people per square mile.
The population of Jefferson County has declined 6.8% since 2010 (38,757 → 36,107), a -0.50% annualized rate.
The median household income in Jefferson County, Illinois is $61,102, with mean (average) household income of $77,553 and per-capita income of $31,541. 11.4% of residents live below the federal poverty level.
In Jefferson County, the largest racial and ethnic groups are White (84.9%), Black or African American (6.5%), Hispanic or Latino (2.2%). Figures are from the US Census Bureau's 2023 ACS 5-year estimates and reflect self-reported responses.
The median age in Jefferson County, Illinois is 41.1 years. Residents are 48.5% female and 51.5% male.
The median home value in Jefferson County is $118,400 and median monthly rent is $862. 71.9% of occupied housing units are owner-occupied. The county has 16,650 total housing units, 11.1% of which are vacant.
The largest employment sector in Jefferson County, Illinois is professional, scientific, and management services, employing 24.3% of workers. The unemployment rate is 3.8%.
Chicago is among the largest cities associated with Jefferson County, Illinois, with a population of 2,707,648.
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Statewide data for Illinois
Population, race, income, age, and trends across Illinois
Data from the American Community Survey (ACS) 5-Year estimates.
Source: U.S. Census Bureau ACS, 2026.