Stephenson County, Illinois Population 2026
Updated April 2026 · US Census ACS 2023 5-Year Estimates · 33rd-largest in Illinois
The population of Stephenson County, Illinois is 44,042 as of the 2023 American Community Survey, making it the 33rd-largest county in Illinois. The median household income is $61,943, the median home value is $127,500, and the median age is 45.2.
The population of Stephenson County has declined 9.5% since 2010 (47,606 → 43,088), a -0.71% annualized rate.
44,042
Population
-0.71%
Annual growth
78
People / sq mi
$61,943
Median Income
$127,500
Median Home Value
Stephenson County covers 564 sq mi of land at 78.1 people per square mile.
About Stephenson County, IL
Stephenson County skews on age — the median resident is 45.2, older than the national median. With 44,042 residents, Stephenson County is a county in Illinois. It ranks #33 among counties in Illinois by population.
Median household income is $61,943, below the US median of $78,538. The poverty rate is 8.9%, below the national 12.4%. Homes are comparatively cheap — a median value of $127,500, with typical rent around $764.
Degree attainment is mid-range for US counties: 21.7% of adults hold a four-year degree, below the national 35.0%. A solid 10.2% of workers are based at home, below the national 14.0%, and the average commute runs about 21 minutes each way.
The age structure shapes everything downstream in Stephenson County — from housing demand to the mix of working-age earners reflected in the income figures above.
Stephenson County Population History (2010-2024)
The county of Stephenson County had a population of 47,606 in 2010 and 43,088 in 2024, a -9.5% growth over 14 years. The peak was 47,606 in 2010. Average annual growth rate: -0.71%.
43,088
Population (2024)
47,606
Population (2010)
47,606
Peak (2010)
-0.71%
Avg Annual Growth
| Year | Population |
|---|---|
| 2010 | 47,606 |
| 2011 | 47,328 |
| 2012 | 46,895 |
| 2013 | 46,683 |
| 2014 | 46,280 |
| 2015 | 45,680 |
| 2016 | 45,512 |
| 2017 | 44,998 |
| 2018 | 44,702 |
| 2019 | 44,371 |
| 2020 | 44,573 |
| 2021 | 44,130 |
| 2022 | 43,702 |
| 2023 | 43,347 |
| 2024 | 43,088 |
Race & Ethnicity
| White | 82.1% |
| Black or African American | 8.4% |
| Asian | 0.0% |
| Hispanic or Latino (any race) | 0.7% |
| Two or More Races | 0.0% |
Age & Sex
45.2
Median Age
51.2%
Female
48.8%
Male
23.9%
Age 65+
Age Distribution
Children (under 15): 17.3% · Seniors (65+): 23.9%
Income & Poverty
| Median household income | $61,943$-19,759 vs state |
| Mean household income | $78,072 |
| Per-capita income | $34,672 |
| Poverty rate | 8.9%+0.7% vs state |
| Unemployment rate | 2.8% |
| Employment-to-population | 56.7% |
Top Industries by Employment
The largest employment sector in Stephenson County is professional & business services, accounting for 26.7% of workers.
How residents commute
0.7%
Drive alone
2.6%
Carpool
77.2%
Public transit
10.2%
Work from home
20.9 min
Avg commute
Housing
$127,500$-123,000 vs state
Median home value
$764
Median rent
71.0%
Homeownership rate
21,375
Total housing units
91.1%
Occupied
8.9%
Vacant
29.0%
Renter-occupied
Social & access
94.8%
With health insurance
90.6%
With broadband internet
27.0%
Foreign-born
7.0%
Veterans (18+)
15.5%
With a disability
95.9%
Speak language other than English at home
Education
91.5%
High School+
21.7%
Bachelor's+
Largest cities in Illinois
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County rankings
Frequently Asked Questions
Stephenson County, Illinois has a population of 44,042 according to the US Census Bureau's 2023 American Community Survey 5-year estimates, making it the 33rd-largest county in Illinois. Population density is 78 people per square mile.
The population of Stephenson County has declined 9.5% since 2010 (47,606 → 43,088), a -0.71% annualized rate.
The median household income in Stephenson County, Illinois is $61,943, with mean (average) household income of $78,072 and per-capita income of $34,672. 8.9% of residents live below the federal poverty level.
In Stephenson County, the largest racial and ethnic groups are White (82.1%), Black or African American (8.4%), Hispanic or Latino (0.7%). Figures are from the US Census Bureau's 2023 ACS 5-year estimates and reflect self-reported responses.
The median age in Stephenson County, Illinois is 45.2 years. Residents are 51.2% female and 48.8% male.
The median home value in Stephenson County is $127,500 and median monthly rent is $764. 71.0% of occupied housing units are owner-occupied. The county has 21,375 total housing units, 8.9% of which are vacant.
The largest employment sector in Stephenson County, Illinois is professional, scientific, and management services, employing 26.7% of workers. The unemployment rate is 2.8%.
Chicago is among the largest cities associated with Stephenson County, Illinois, with a population of 2,707,648.
Stephenson County, IL Climate
Stephenson County, IL has an average annual temperature of 8.2°C (47°F) and receives about 863 mm of precipitation per year. The warmest month is July and the coldest is January. Figures are 1970–2000 climate normals.
8.2°C
Avg Temp
863
Precip (mm/yr)
Jul
Hottest Month
Jan
Coldest Month
| Month | Avg (°C/°F) | Precip |
|---|---|---|
| January | -8° / 17° | 30 mm |
| February | -5° / 22° | 29 mm |
| March | 1° / 34° | 58 mm |
| April | 8° / 47° | 81 mm |
| May | 15° / 59° | 94 mm |
| June | 20° / 68° | 104 mm |
| July | 22° / 72° | 93 mm |
| August | 21° / 70° | 103 mm |
| September | 17° / 62° | 98 mm |
| October | 10° / 50° | 66 mm |
| November | 2° / 36° | 61 mm |
| December | -5° / 23° | 46 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 Stephenson County, IL
The most comfortable months to visit Stephenson County, IL are typically August, July and June, when temperatures are mildest and rainfall is relatively low. The hottest month is July (around 28°C high). The coldest is January (near -13°C low). June is usually the wettest month.
Where to stay near Stephenson County
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Data from the American Community Survey (ACS) 5-Year estimates.
Source: U.S. Census Bureau ACS, 2026.