Clay County, Illinois Population 2026
Updated April 2026 · US Census ACS 2023 5-Year Estimates · 80th-largest in Illinois
The population of Clay County, Illinois is 13,173 as of the 2023 American Community Survey, making it the 80th-largest county in Illinois. The median household income is $57,266, the median home value is $94,300, and the median age is 41.5.
The population of Clay County has declined 7.2% since 2010 (13,822 → 12,821), a -0.54% annualized rate.
13,173
Population
-0.54%
Annual growth
28
People / sq mi
$57,266
Median Income
$94,300
Median Home Value
Clay County covers 468 sq mi of land at 28.1 people per square mile.
About Clay County, IL
Housing cost is the defining feature of Clay County: the median home is valued at $94,300. With 13,173 residents, Clay County is a county in Illinois.
The typical household here earns about $57,266, below the US median of $78,538. About 10.9% of residents live below the federal poverty level, below the national 12.4%. Home prices sit near the bottom of the range at $94,300, with typical rent around $709.
College attainment is 15.6%, below the national 35.0%. Around 6.2% of workers work from home, below the national 14.0%, and the average commute runs about 26 minutes each way.
Clay County Population History (2010-2024)
The county of Clay County had a population of 13,822 in 2010 and 12,821 in 2024, a -7.2% growth over 14 years. The peak was 13,822 in 2010. Average annual growth rate: -0.53%.
12,821
Population (2024)
13,822
Population (2010)
13,822
Peak (2010)
-0.53%
Avg Annual Growth
| Year | Population |
|---|---|
| 2010 | 13,822 |
| 2011 | 13,721 |
| 2012 | 13,710 |
| 2013 | 13,550 |
| 2014 | 13,441 |
| 2015 | 13,395 |
| 2016 | 13,309 |
| 2017 | 13,259 |
| 2018 | 13,260 |
| 2019 | 13,177 |
| 2020 | 13,273 |
| 2021 | 13,166 |
| 2022 | 13,053 |
| 2023 | 12,945 |
| 2024 | 12,821 |
Race & Ethnicity
| White | 95.4% |
| Black or African American | 0.7% |
| Asian | 0.0% |
| Hispanic or Latino (any race) | 2.0% |
| Two or More Races | 0.0% |
Age & Sex
41.5
Median Age
49.9%
Female
50.1%
Male
20.7%
Age 65+
Age Distribution
Children (under 15): 18.6% · Seniors (65+): 20.7%
Income & Poverty
| Median household income | $57,266$-24,436 vs state |
| Mean household income | $79,425 |
| Per-capita income | $33,212 |
| Poverty rate | 10.9%+2.7% vs state |
| Unemployment rate | 3.3% |
| Employment-to-population | 53.3% |
Top Industries by Employment
The largest employment sector in Clay County is manufacturing, accounting for 24.4% of workers.
How residents commute
0.3%
Drive alone
0.8%
Carpool
85.5%
Public transit
6.2%
Work from home
26.1 min
Avg commute
Housing
$94,300$-156,200 vs state
Median home value
$709
Median rent
80.7%
Homeownership rate
6,147
Total housing units
88.4%
Occupied
11.6%
Vacant
19.3%
Renter-occupied
Social & access
94.4%
With health insurance
90.9%
With broadband internet
12.4%
Foreign-born
8.1%
Veterans (18+)
18.6%
With a disability
98.9%
Speak language other than English at home
Education
87.7%
High School+
15.6%
Bachelor's+
Largest cities in Illinois
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County rankings
Frequently Asked Questions
Clay County, Illinois has a population of 13,173 according to the US Census Bureau's 2023 American Community Survey 5-year estimates, making it the 80th-largest county in Illinois. Population density is 28 people per square mile.
The population of Clay County has declined 7.2% since 2010 (13,822 → 12,821), a -0.54% annualized rate.
The median household income in Clay County, Illinois is $57,266, with mean (average) household income of $79,425 and per-capita income of $33,212. 10.9% of residents live below the federal poverty level.
In Clay County, the largest racial and ethnic groups are White (95.4%), Hispanic or Latino (2.0%), Black or African American (0.7%). Figures are from the US Census Bureau's 2023 ACS 5-year estimates and reflect self-reported responses.
The median age in Clay County, Illinois is 41.5 years. Residents are 49.9% female and 50.1% male.
The median home value in Clay County is $94,300 and median monthly rent is $709. 80.7% of occupied housing units are owner-occupied. The county has 6,147 total housing units, 11.6% of which are vacant.
The largest employment sector in Clay County, Illinois is manufacturing, employing 24.4% of workers. The unemployment rate is 3.3%.
Chicago is among the largest cities associated with Clay County, Illinois, with a population of 2,707,648.
Clay County, IL Climate
Clay County, IL has an average annual temperature of 12.5°C (55°F) and receives about 1066 mm of precipitation per year. The warmest month is July and the coldest is January. Figures are 1970–2000 climate normals.
12.5°C
Avg Temp
1066
Precip (mm/yr)
Jul
Hottest Month
Jan
Coldest Month
| Month | Avg (°C/°F) | Precip |
|---|---|---|
| January | -2° / 28° | 57 mm |
| February | 1° / 33° | 62 mm |
| March | 7° / 44° | 107 mm |
| April | 13° / 55° | 102 mm |
| May | 18° / 64° | 111 mm |
| June | 23° / 73° | 105 mm |
| July | 25° / 77° | 99 mm |
| August | 24° / 75° | 81 mm |
| September | 20° / 69° | 77 mm |
| October | 14° / 57° | 77 mm |
| November | 7° / 45° | 97 mm |
| December | 1° / 34° | 91 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 Clay County, IL
The most comfortable months to visit Clay County, IL are typically September, August and June, when temperatures are mildest and rainfall is relatively low. The hottest month is July (around 32°C high). The coldest is January (near -7°C low). May is usually the wettest month.
Where to stay near Clay County
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Data from the American Community Survey (ACS) 5-Year estimates.
Source: U.S. Census Bureau ACS, 2026.