Union County, Illinois Population 2026
Updated April 2026 · US Census ACS 2023 5-Year Estimates · 61st-largest in Illinois
The population of Union County, Illinois is 16,972 as of the 2023 American Community Survey, making it the 61st-largest county in Illinois. The median household income is $56,420, the median home value is $131,700, and the median age is 44.3.
The population of Union County has declined 4.8% since 2010 (17,729 → 16,886), a -0.35% annualized rate.
16,972
Population
-0.35%
Annual growth
41
People / sq mi
$56,420
Median Income
$131,700
Median Home Value
Union County covers 413 sq mi of land at 41.1 people per square mile.
About Union County, IL
Age is the most distinctive thing about Union County: a median age of 44.3, older than the national median. Union County is a county in Illinois with a population of 16,972.
Household earnings are middling, with a median of $56,420 — below the US median of $78,538. Roughly 12.4% of residents fall below the poverty line, close to the national 12.4%. Housing is relatively affordable, with a median home value of $131,700, with typical rent around $658.
Degree attainment is mid-range for US counties: 20.9% of adults hold a four-year degree, below the national 35.0%. Just 5.6% of workers are home-based, below the national 14.0%, and the average commute runs about 26 minutes each way.
The age structure shapes everything downstream in Union County — from housing demand to the mix of working-age earners reflected in the income figures above.
Union County Population History (2010-2024)
The county of Union County had a population of 17,729 in 2010 and 16,886 in 2024, a -4.8% growth over 14 years. The peak was 17,729 in 2010. Average annual growth rate: -0.34%.
16,886
Population (2024)
17,729
Population (2010)
17,729
Peak (2010)
-0.34%
Avg Annual Growth
| Year | Population |
|---|---|
| 2010 | 17,729 |
| 2011 | 17,690 |
| 2012 | 17,609 |
| 2013 | 17,541 |
| 2014 | 17,404 |
| 2015 | 17,285 |
| 2016 | 17,120 |
| 2017 | 16,982 |
| 2018 | 16,853 |
| 2019 | 16,693 |
| 2020 | 17,298 |
| 2021 | 17,035 |
| 2022 | 16,901 |
| 2023 | 16,866 |
| 2024 | 16,886 |
Race & Ethnicity
| White | 90.5% |
| Black or African American | 0.8% |
| Asian | 0.0% |
| Hispanic or Latino (any race) | 1.4% |
| Two or More Races | 0.1% |
Age & Sex
44.3
Median Age
49.1%
Female
50.9%
Male
22.0%
Age 65+
Age Distribution
Children (under 15): 17.0% · Seniors (65+): 22.0%
Income & Poverty
| Median household income | $56,420$-25,282 vs state |
| Mean household income | $75,913 |
| Per-capita income | $31,962 |
| Poverty rate | 12.4%+4.2% vs state |
| Unemployment rate | 2.7% |
| Employment-to-population | 48.4% |
Top Industries by Employment
The largest employment sector in Union County is professional & business services, accounting for 28.8% of workers.
How residents commute
0.0%
Drive alone
1.1%
Carpool
84.1%
Public transit
5.6%
Work from home
25.9 min
Avg commute
Housing
$131,700$-118,800 vs state
Median home value
$658
Median rent
76.8%
Homeownership rate
7,861
Total housing units
88.0%
Occupied
12.0%
Vacant
23.2%
Renter-occupied
Social & access
93.4%
With health insurance
82.0%
With broadband internet
26.8%
Foreign-born
7.1%
Veterans (18+)
19.3%
With a disability
94.7%
Speak language other than English at home
Education
87.0%
High School+
20.9%
Bachelor's+
Largest cities in Illinois
Other counties in Illinois
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County rankings
Frequently Asked Questions
Union County, Illinois has a population of 16,972 according to the US Census Bureau's 2023 American Community Survey 5-year estimates, making it the 61st-largest county in Illinois. Population density is 41 people per square mile.
The population of Union County has declined 4.8% since 2010 (17,729 → 16,886), a -0.35% annualized rate.
The median household income in Union County, Illinois is $56,420, with mean (average) household income of $75,913 and per-capita income of $31,962. 12.4% of residents live below the federal poverty level.
In Union County, the largest racial and ethnic groups are White (90.5%), Hispanic or Latino (1.4%), Black or African American (0.8%). Figures are from the US Census Bureau's 2023 ACS 5-year estimates and reflect self-reported responses.
The median age in Union County, Illinois is 44.3 years. Residents are 49.1% female and 50.9% male.
The median home value in Union County is $131,700 and median monthly rent is $658. 76.8% of occupied housing units are owner-occupied. The county has 7,861 total housing units, 12.0% of which are vacant.
The largest employment sector in Union County, Illinois is professional, scientific, and management services, employing 28.8% of workers. The unemployment rate is 2.7%.
Chicago is among the largest cities associated with Union County, Illinois, with a population of 2,707,648.
Union County, IL Climate
Union County, IL has an average annual temperature of 13.5°C (56°F) and receives about 1206 mm of precipitation per year. The warmest month is July and the coldest is January. Figures are 1970–2000 climate normals.
13.5°C
Avg Temp
1206
Precip (mm/yr)
Jul
Hottest Month
Jan
Coldest Month
| Month | Avg (°C/°F) | Precip |
|---|---|---|
| January | 0° / 31° | 80 mm |
| February | 2° / 36° | 85 mm |
| March | 8° / 46° | 122 mm |
| April | 14° / 56° | 118 mm |
| May | 19° / 65° | 128 mm |
| June | 23° / 74° | 105 mm |
| July | 26° / 78° | 87 mm |
| August | 25° / 76° | 93 mm |
| September | 21° / 70° | 83 mm |
| October | 15° / 58° | 83 mm |
| November | 8° / 47° | 115 mm |
| December | 3° / 37° | 107 mm |
1970–2000 normals from WorldClim 2.1 (~9 km grid). Precipitation can be less precise near mountains or coastlines, where rainfall varies sharply over short distances.
Best time to visit Union County, IL
The most comfortable months to visit Union County, IL are typically September, June and August, when temperatures are mildest and rainfall is relatively low. The hottest month is July (around 32°C high). The coldest is January (near -5°C low). May is usually the wettest month.
Where to stay near Union County
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Data from the American Community Survey (ACS) 5-Year estimates.
Source: U.S. Census Bureau ACS, 2026.