Warren County, Illinois Demographics 2026

Population Overview

Warren County is located in Illinois with a total population of 16,447. It is the 65th most populous county out of 102 in Illinois. The county encompasses 6 Census-designated places.

Age Demographics

The median age in Warren County is 38.5 years. This is 1% lower than the state median of 39.0 years.

Economy, Income & Housing

The median household income in Warren County is $67,385. This is 19% lower than the state median of $83,390. It is also 17% lower than the national median of $80,734. The poverty rate stands at 14.6%. This is 24% higher than the state poverty rate of 11.8%. The unemployment rate is 3.6%. This is 39% lower than the state rate of 5.8%. The median home value is $105,000. Housing costs are 60% lower than the state median of $263,300. With a home-value-to-income ratio of just 1.6x, Warren County is one of the most affordable housing markets in the area. 75.2% of occupied housing units are owner-occupied. This homeownership rate is 12% higher than the state average of 67.1%.

Race & Ethnicity

The largest racial or ethnic group in Warren County is White (non-Hispanic), making up 81.1% of the population. Hispanic or Latino residents account for 11.1%. The Black or African American population (2.7%) is well below the state average of 13.3%. The Asian population (2.4%) is well below the state average of 5.9%.

Education

22.0% of residents aged 25 and older hold a bachelor's degree or higher. This is 42% 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 87.1%.

Data Sources & Methodology

All figures for Warren 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.