Williamson County, Illinois Demographics 2026

Population Overview

Williamson County is located in Illinois with a total population of 66,902. It is the 22nd most populous county out of 102 in Illinois.

Age Demographics

The median age in Williamson County is 41.4 years. This is 6% higher than the state median of 38.9 years.

Economy, Income & Housing

The median household income in Williamson County is $65,521. This is 20% lower than the state median of $81,702. Compared to the national median of $78,538, household income here is 17% lower. The poverty rate stands at 14.3%. This is 22% higher than the state poverty rate of 11.7%. The unemployment rate is 4.3%. This is 25% lower than the state rate of 5.8%. The median home value is $145,600. Housing costs are 42% lower than the state median of $250,500. With a home-value-to-income ratio of just 2.2x, Williamson County is one of the most affordable housing markets in the area. 71.1% of occupied housing units are owner-occupied. This homeownership rate is 6% higher than the state average of 66.8%.

Race & Ethnicity

Williamson County has a predominantly White (non-Hispanic) population, comprising 88.2% of all residents. Black or African American residents account for 3.5%. The White (non-Hispanic) population is significantly higher than the state average (88.2% vs 58.8%). The Black or African American population (3.5%) is well below the state average of 13.6%. The Hispanic or Latino population (2.8%) is well below the state average of 18.5%. The Asian population (1.5%) is well below the state average of 5.8%.

Education

27.5% of residents aged 25 and older hold a bachelor's degree or higher. This is 26% lower than the state rate of 37.2%. Nationally, 35.0% of adults hold at least a bachelor's degree. The high school graduation rate (or equivalent) is 92.4%.