Mason County, Illinois Population 2026
Updated April 2026 · US Census ACS 2023 5-Year Estimates · 81st-largest in Illinois
The population of Mason County, Illinois is 12,878 as of the 2023 American Community Survey, making it the 81st-largest county in Illinois. The median household income is $62,127, the median home value is $106,100, and the median age is 45.5.
The population of Mason County has declined 14.4% since 2010 (14,651 → 12,543), a -1.10% annualized rate.
12,878
Population
-1.10%
Annual growth
24
People / sq mi
$62,127
Median Income
$106,100
Median Home Value
Mason County covers 539 sq mi of land at 23.9 people per square mile.
About Mason County, IL
Mason County is a county in Illinois with a population of 12,878. It ranks #81 among counties in Illinois by population. The median age is 45.5, older than the national median. The population is 49.3% male and 50.7% female.
The median household income in Mason County is $62,127, below the US median of $74,580. 10.1% of residents live below the federal poverty level. Home values sit at a median of $106,100, with monthly rent averaging $760. The homeownership rate of 80.6% is higher than the national rate of 64.8%.
Educational attainment in Mason County reflects 17.1% of adults 25 and older holding a bachelor's degree or higher, below the national average of 34.3%. Roughly 8.2% of workers primarily work from home, below the national work-from-home rate of 14.2%. The average commute is 28.8 minutes each way.
Mason County Population History (2010-2024)
The county of Mason County had a population of 14,651 in 2010 and 12,543 in 2024, a -14.4% growth over 14 years. The peak was 14,651 in 2010. Average annual growth rate: -1.10%.
12,543
Population (2024)
14,651
Population (2010)
14,651
Peak (2010)
-1.10%
Avg Annual Growth
| Year | Population |
|---|---|
| 2010 | 14,651 |
| 2011 | 14,470 |
| 2012 | 14,322 |
| 2013 | 14,144 |
| 2014 | 14,102 |
| 2015 | 13,862 |
| 2016 | 13,677 |
| 2017 | 13,672 |
| 2018 | 13,520 |
| 2019 | 13,387 |
| 2020 | 13,053 |
| 2021 | 12,826 |
| 2022 | 12,717 |
| 2023 | 12,588 |
| 2024 | 12,543 |
Race & Ethnicity
| White | 96.0% |
| Black or African American | 0.9% |
| Asian | 0.0% |
| Hispanic or Latino (any race) | 0.7% |
| Two or More Races | 0.0% |
Age & Sex
45.5
Median Age
50.7%
Female
49.3%
Male
23.0%
Age 65+
Age Distribution
Children (under 15): 16.6% · Seniors (65+): 23.0%
Income & Poverty
| Median household income | $62,127$-19,575 vs state |
| Mean household income | $78,688 |
| Per-capita income | $34,783 |
| Poverty rate | 10.1%+1.9% vs state |
| Unemployment rate | 3.4% |
| Employment-to-population | 53.3% |
Top Industries by Employment
The largest employment sector in Mason County is professional & business services, accounting for 22.6% of workers.
How residents commute
0.2%
Drive alone
1.5%
Carpool
81.4%
Public transit
8.2%
Work from home
28.8 min
Avg commute
Housing
$106,100$-144,400 vs state
Median home value
$760
Median rent
80.6%
Homeownership rate
6,615
Total housing units
86.4%
Occupied
13.6%
Vacant
19.4%
Renter-occupied
Social & access
95.4%
With health insurance
90.8%
With broadband internet
10.8%
Foreign-born
7.7%
Veterans (18+)
17.1%
With a disability
98.1%
Speak language other than English at home
Education
92.1%
High School+
17.1%
Bachelor's+
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Other counties in Illinois
Part of Illinois
Metro areas in Illinois
County rankings
Frequently Asked Questions
Mason County, Illinois has a population of 12,878 according to the US Census Bureau's 2023 American Community Survey 5-year estimates, making it the 81st-largest county in Illinois. Population density is 24 people per square mile.
The population of Mason County has declined 14.4% since 2010 (14,651 → 12,543), a -1.10% annualized rate.
The median household income in Mason County, Illinois is $62,127, with mean (average) household income of $78,688 and per-capita income of $34,783. 10.1% of residents live below the federal poverty level.
In Mason County, the largest racial and ethnic groups are White (96.0%), Black or African American (0.9%), 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 Mason County, Illinois is 45.5 years. Residents are 50.7% female and 49.3% male.
The median home value in Mason County is $106,100 and median monthly rent is $760. 80.6% of occupied housing units are owner-occupied. The county has 6,615 total housing units, 13.6% of which are vacant.
The largest employment sector in Mason County, Illinois is professional, scientific, and management services, employing 22.6% of workers. The unemployment rate is 3.4%.
Chicago is among the largest cities associated with Mason 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.