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
What sets Jefferson County apart is where people work — remote work is unusually rare here, at 4.8% versus 14.0% nationally. Jefferson County is a county in Illinois with a population of 36,808. It ranks #38 among counties in Illinois by population.
The typical household here earns about $61,102, below the US median of $78,538. The poverty rate is 11.4%, below the national 12.4%. Homes are comparatively cheap — a median value of $118,400, with typical rent around $862.
Degree attainment is mid-range for US counties: 18.4% of adults hold a four-year degree, below the national 35.0%. Remote work is on the lower side here, at 4.8%, below the national 14.0%, and the average commute runs about 20 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+
Largest cities in Illinois
Other counties in Illinois
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.