Mason County, Illinois Demographics 2026

Population Overview

Mason County is located in Illinois with a total population of 12,745. It is the 82nd most populous county out of 102 in Illinois. The county encompasses 9 Census-designated places.

Age Demographics

The median age in Mason County is 45.4 years. This is 16% higher than the state median of 39.0 years. 10.2% of residents are 75 or older, suggesting a significant retirement-age population with implications for healthcare services and senior housing.

Economy, Income & Housing

The median household income in Mason County is $62,845. This is 25% lower than the state median of $83,390. It is also 22% lower than the national median of $80,734. The poverty rate stands at 14.8%. This is 26% higher than the state poverty rate of 11.8%. The unemployment rate is 4.9%. This is 17% lower than the state rate of 5.8%. The median home value is $103,400. Housing costs are 61% lower than the state median of $263,300. With a home-value-to-income ratio of just 1.6x, Mason County is one of the most affordable housing markets in the area. 81.8% of occupied housing units are owner-occupied. This homeownership rate is 22% higher than the state average of 67.1%.

Race & Ethnicity

Mason County has a predominantly White (non-Hispanic) population, comprising 94.2% of all residents. Hispanic or Latino residents account for 1.6%. The White (non-Hispanic) population is significantly higher than the state average (94.2% vs 58.1%). The Black or African American population (0.5%) is well below the state average of 13.3%. The Hispanic or Latino population (1.6%) is well below the state average of 18.8%. The Asian population (0.4%) is well below the state average of 5.9%.

Education

17.1% of residents aged 25 and older hold a bachelor's degree or higher. This is 55% lower than the state rate of 37.9%. Nationally, 35.7% of adults hold at least a bachelor's degree. The high school graduation rate (or equivalent) is 93.0%.

Data Sources & Methodology

All figures for Mason County come from the U.S. Census Bureau's American Community Survey (ACS) 2020–2024 5-Year Estimates, with comparisons drawn against Illinois and national averages from the same dataset. See our methodology page for how each metric is defined, or data.census.gov for official tables with margins of error.