Jefferson County, Illinois Demographics 2026

Population Overview

Jefferson County is located in Illinois with a total population of 36,808. It is the 38th most populous county out of 102 in Illinois.

Age Demographics

The median age in Jefferson County is 41.1 years. This is 6% higher than the state median of 38.9 years.

Economy, Income & Housing

The median household income in Jefferson County is $61,102. This is 25% lower than the state median of $81,702. Compared to the national median of $78,538, household income here is 22% lower. The poverty rate stands at 14.2%. This is 21% higher than the state poverty rate of 11.7%. The unemployment rate is 6.6%. This is 13% higher than the state rate of 5.8%. The median home value is $118,400. Housing costs are 53% lower than the state median of $250,500. With a home-value-to-income ratio of just 1.9x, Jefferson County is one of the most affordable housing markets in the area. 71.9% of occupied housing units are owner-occupied. This homeownership rate is 7% higher than the state average of 66.8%.

Race & Ethnicity

The largest racial or ethnic group in Jefferson County is White (non-Hispanic), making up 84.3% of the population. Black or African American residents account for 6.2%. The Black or African American population (6.2%) is well below the state average of 13.6%. The Hispanic or Latino population (2.7%) is well below the state average of 18.5%. The Asian population (0.9%) is well below the state average of 5.8%.

Education

18.4% of residents aged 25 and older hold a bachelor's degree or higher. This is 51% 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 91.4%.