O'Fallon city, Illinois Demographics & Population 2026

Population Overview

O'Fallon city is a mid-sized community located in Illinois. The total population is 32,139. It ranks as the 58th most populous out of 1,445 cities and towns in Illinois.

Age Demographics

The median age in O'Fallon city is 36.9 years. This is 5% lower than the state median of 38.9 years. With 28.7% of the population under 18, O'Fallon city has a notably young demographic profile, suggesting a family-oriented community.

Economy, Income & Housing

The median household income in O'Fallon city is $102,793. This is 26% higher than the state median of $81,702. Compared to the national median of $78,538, household income here is 31% higher. The poverty rate stands at 4.4%. This is 63% lower than the state poverty rate of 11.7%. This exceptionally low poverty rate indicates strong economic prosperity across the community. The unemployment rate is 3.3%. This is 42% lower than the state rate of 5.8%. The median home value is $274,100. Housing costs are 9% higher than the state median of $250,500. With a home-value-to-income ratio of just 2.7x, O'Fallon city is one of the most affordable housing markets in the area. 70.9% of occupied housing units are owner-occupied. This homeownership rate is 6% higher than the state average of 66.8%.

Race & Ethnicity

The largest racial or ethnic group in O'Fallon city is White (non-Hispanic), making up 70.3% of the population. Black or African American residents account for 13.5%. The Hispanic or Latino population (6.0%) is well below the state average of 18.5%. The Asian population (2.9%) is well below the state average of 5.8%.

Education

51.2% of residents aged 25 and older hold a bachelor's degree or higher. This places O'Fallon city in the top 10% of all cities in the state for educational attainment. This is 38% higher 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 97.0%. Notably, 23.3% of adults hold a graduate or professional degree, indicating a highly educated workforce.

Data Sources & Methodology

All demographic data for O'Fallon city, Illinois is sourced from the U.S. Census Bureau's American Community Survey (ACS) 5-Year Estimates (2019-2023). The ACS collects data from approximately 3.5 million households annually, providing reliable estimates for communities of all sizes. Comparisons are made against Illinois state averages and national averages calculated from the same dataset. Rankings reflect the city's position among all 1,445 Census-designated places in Illinois. For official data, visit data.census.gov.