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 distinguished by its share of foreign-born residents, 10.8% of the population. Mason County is a county in Illinois with a population of 12,878.
The typical household here earns about $62,127, below the US median of $78,538. Poverty runs at 10.1%, below the national 12.4%. Housing is relatively affordable, with a median home value of $106,100, with typical rent around $760.
Degree attainment is on the lower side for US counties: 17.1% of adults hold a bachelor’s degree, below the national 35.0%. About 8.2% of the workforce is home-based, below the national 14.0%, and the average commute runs about 29 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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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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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.