Knox County, Illinois Population 2026
Updated April 2026 · US Census ACS 2023 5-Year Estimates · 29th-largest in Illinois
The population of Knox County, Illinois is 49,294 as of the 2023 American Community Survey, making it the 29th-largest county in Illinois. The median household income is $53,291, the median home value is $104,900, and the median age is 42.4.
The population of Knox County has declined 7.9% since 2010 (52,911 → 48,716), a -0.59% annualized rate.
49,294
Population
-0.59%
Annual growth
69
People / sq mi
$53,291
Median Income
$104,900
Median Home Value
Knox County covers 716 sq mi of land at 68.8 people per square mile.
About Knox County, IL
In Knox County, home values do the distinguishing — a median of $104,900. With 49,294 residents, Knox County is a county in Illinois. It ranks #29 among counties in Illinois by population.
The typical household earns $53,291, below the US median of $78,538. About 10.5% of residents live below the federal poverty level, below the national 12.4%. Housing is relatively affordable, with a median home value of $104,900, with typical rent around $725.
Roughly 20.3% of adults have a bachelor’s, below the national 35.0%. Most workers commute: only 5.7% work from home, below the national 14.0%, and the average commute runs about 21 minutes each way.
Knox County Population History (2010-2024)
The county of Knox County had a population of 52,911 in 2010 and 48,716 in 2024, a -7.9% growth over 14 years. The peak was 52,911 in 2010. Average annual growth rate: -0.59%.
48,716
Population (2024)
52,911
Population (2010)
52,911
Peak (2010)
-0.59%
Avg Annual Growth
| Year | Population |
|---|---|
| 2010 | 52,911 |
| 2011 | 52,702 |
| 2012 | 52,302 |
| 2013 | 52,130 |
| 2014 | 51,945 |
| 2015 | 51,377 |
| 2016 | 50,931 |
| 2017 | 50,601 |
| 2018 | 50,008 |
| 2019 | 49,669 |
| 2020 | 49,806 |
| 2021 | 49,333 |
| 2022 | 48,713 |
| 2023 | 48,663 |
| 2024 | 48,716 |
Race & Ethnicity
| White | 83.3% |
| Black or African American | 7.8% |
| Asian | 0.0% |
| Hispanic or Latino (any race) | 0.7% |
| Two or More Races | 0.0% |
Age & Sex
42.4
Median Age
48.9%
Female
51.1%
Male
22.2%
Age 65+
Age Distribution
Children (under 15): 16.6% · Seniors (65+): 22.2%
Income & Poverty
| Median household income | $53,291$-28,411 vs state |
| Mean household income | $69,635 |
| Per-capita income | $29,614 |
| Poverty rate | 10.5%+2.3% vs state |
| Unemployment rate | 2.4% |
| Employment-to-population | 51.3% |
Top Industries by Employment
The largest employment sector in Knox County is professional & business services, accounting for 31.7% of workers.
How residents commute
0.5%
Drive alone
3.6%
Carpool
80.5%
Public transit
5.7%
Work from home
20.6 min
Avg commute
Housing
$104,900$-145,600 vs state
Median home value
$725
Median rent
69.8%
Homeownership rate
23,788
Total housing units
87.3%
Occupied
12.7%
Vacant
30.2%
Renter-occupied
Social & access
94.5%
With health insurance
87.9%
With broadband internet
16.3%
Foreign-born
7.1%
Veterans (18+)
14.7%
With a disability
94.1%
Speak language other than English at home
Education
89.3%
High School+
20.3%
Bachelor's+
Largest cities in Illinois
Other counties in Illinois
Part of Illinois
Metro areas in Illinois
County rankings
Frequently Asked Questions
Knox County, Illinois has a population of 49,294 according to the US Census Bureau's 2023 American Community Survey 5-year estimates, making it the 29th-largest county in Illinois. Population density is 69 people per square mile.
The population of Knox County has declined 7.9% since 2010 (52,911 → 48,716), a -0.59% annualized rate.
The median household income in Knox County, Illinois is $53,291, with mean (average) household income of $69,635 and per-capita income of $29,614. 10.5% of residents live below the federal poverty level.
In Knox County, the largest racial and ethnic groups are White (83.3%), Black or African American (7.8%), 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 Knox County, Illinois is 42.4 years. Residents are 48.9% female and 51.1% male.
The median home value in Knox County is $104,900 and median monthly rent is $725. 69.8% of occupied housing units are owner-occupied. The county has 23,788 total housing units, 12.7% of which are vacant.
The largest employment sector in Knox County, Illinois is professional, scientific, and management services, employing 31.7% of workers. The unemployment rate is 2.4%.
Chicago is among the largest cities associated with Knox County, Illinois, with a population of 2,707,648.
Knox County, IL Climate
Knox County, IL has an average annual temperature of 10°C (50°F) and receives about 947 mm of precipitation per year. The warmest month is July and the coldest is January. Figures are 1970–2000 climate normals.
10°C
Avg Temp
947
Precip (mm/yr)
Jul
Hottest Month
Jan
Coldest Month
| Month | Avg (°C/°F) | Precip |
|---|---|---|
| January | -6° / 21° | 37 mm |
| February | -3° / 27° | 35 mm |
| March | 4° / 38° | 72 mm |
| April | 10° / 50° | 97 mm |
| May | 16° / 61° | 100 mm |
| June | 21° / 71° | 107 mm |
| July | 24° / 75° | 108 mm |
| August | 23° / 73° | 98 mm |
| September | 18° / 65° | 96 mm |
| October | 12° / 53° | 73 mm |
| November | 4° / 39° | 68 mm |
| December | -3° / 27° | 56 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 Knox County, IL
The most comfortable months to visit Knox County, IL are typically June, August and September, when temperatures are mildest and rainfall is relatively low. The hottest month is July (around 30°C high). The coldest is January (near -10°C low). July is usually the wettest month.
Where to stay near Knox County
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Data from the American Community Survey (ACS) 5-Year estimates.
Source: U.S. Census Bureau ACS, 2026.