O'Fallon, Illinois Demographics & Population 2026
During the 2020–2024 ACS period, O'Fallon, Illinois had a total population of 32,262, the 58th largest city in Illinois, with a median household income of $105,982, which is 27% higher than the state average. The poverty rate is 6.2%.
Data vintage: U.S. Census Bureau ACS 2020–2024 5-Year Estimates · refreshed July 2026 · Methodology & source notes
Key Takeaways
- 52.4% of adults hold a bachelor's degree or higher — top 10% in Illinois.
O'Fallon Quick Facts
How O'Fallon Changed
Change from the 2019–2023 ACS period to 2020–2024. These are rolling five-year estimates, not year-over-year measurements.
| Metric | 2019–2023 | 2020–2024 | Change |
|---|---|---|---|
| Population | 32,139 | 32,262 | +0.4% |
| Median household income | $102,793 | $105,982 | +3.1% |
| Median home value | $274,100 | $295,700 | +7.9% |
How O'Fallon Compares
Median Household Income
Median Home Value
Economy & Housing
Household Income Distribution
Detailed income brackets
Employment
Housing Overview
People & Demographics
Age Distribution
Race & Ethnicity
Diversity Index
Moderate diversity with one or two groups making up the majority.
State average: 61 | National average: 61
Education
Educational Attainment (Adults 25+)
O'Fallon Rankings in Illinois
Explore Illinois Rankings
Other Cities in St. Clair County
| City | Population | Median Income | Poverty | Home Value |
|---|---|---|---|---|
| Belleville | 41,370 | $63,535 | 14.6% | $141,300 |
| East St. Louis | 17,999 | $35,700 | 32.8% | $52,600 |
| Fairview Heights | 16,745 | $80,930 | 8.8% | $177,700 |
| Swansea | 14,710 | $91,587 | 8.7% | $223,600 |
| Shiloh | 14,572 | $99,573 | 6.8% | $274,000 |
| Columbia | 11,127 | $107,606 | 5.4% | $293,000 |
| Mascoutah | 8,816 | $97,375 | 9.8% | $224,900 |
| Freeburg | 4,592 | $92,065 | 6.7% | $241,200 |
| Lebanon | 4,474 | $88,750 | 14.8% | $170,700 |
| Caseyville | 4,130 | $60,669 | 14.3% | $96,800 |
Cities Similar to O'Fallon
These cities in the same state have comparable population and economic profiles.
| City | Population | Median Income | Home Value | Bachelor's+ | Poverty |
|---|---|---|---|---|---|
| Mundelein | 31,915 | $108,340 | $309,700 | 46.0% | 8.2% |
| St. Charles | 32,854 | $114,300 | $377,400 | 52.0% | 4.5% |
| Elk Grove Village | 31,987 | $94,175 | $347,100 | 41.2% | 7.9% |
| Woodridge | 33,941 | $101,000 | $363,700 | 46.5% | 5.5% |
| Gurnee | 30,510 | $119,628 | $344,300 | 56.7% | 5.2% |
Population Overview
O'Fallon is a mid-sized community located in Illinois, within St. Clair County. The total population is 32,262. It ranks as the 58th most populous out of 1,445 Census-designated places in Illinois.
Age Demographics
The median age in O'Fallon is 37.8 years. This is 3% lower than the state median of 39.0 years.
Economy, Income & Housing
The median household income in O'Fallon is $105,982. This is 27% higher than the state median of $83,390. It is also 31% higher than the national median of $80,734. The poverty rate stands at 6.2%. This is 48% lower than the state poverty rate of 11.8%. The unemployment rate is 3.7%. This is 37% lower than the state rate of 5.8%. The median home value is $295,700. Housing costs are 12% higher than the state median of $263,300. With a home-value-to-income ratio of just 2.8x, O'Fallon is one of the most affordable housing markets in the area. 70.2% of occupied housing units are owner-occupied. This homeownership rate is 5% higher than the state average of 67.1%.
Race & Ethnicity
The largest racial or ethnic group in O'Fallon is White (non-Hispanic), making up 69.4% of the population. Black or African American residents account for 16.5%. The Hispanic or Latino population (5.1%) is well below the state average of 18.8%. The Asian population (2.6%) is well below the state average of 5.9%.
Education
52.4% of residents aged 25 and older hold a bachelor's degree or higher. This places O'Fallon in the top 10% of all cities in the state for educational attainment. This is 38% higher 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 97.6%. Notably, 23.4% of adults hold a graduate or professional degree, indicating a highly educated workforce.
Data Sources & Methodology
All demographic data for O'Fallon, Illinois is sourced from the U.S. Census Bureau's American Community Survey (ACS) 2020–2024 5-Year Estimates. The ACS collects data from approximately 3.5 million households annually and pools five years of responses so that even small communities can be measured, though the margin of error widens as the population falls. 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. Read more about how these figures are produced on our methodology page, or visit data.census.gov for official data.
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Frequently Asked Questions
What is the population of O'Fallon, Illinois?
O'Fallon, Illinois has a population of 32,262 according to the most recent U.S. Census ACS 5-Year Estimates.
What is the median household income in O'Fallon, IL?
The median household income in O'Fallon is $105,982, which is 31% higher than the national median of $80,734.
What is the poverty rate in O'Fallon, IL?
The poverty rate in O'Fallon is 6.2%. This means approximately 1,990 residents live below the federal poverty line.
What is the racial makeup of O'Fallon, Illinois?
O'Fallon's population is 69.4% White, 16.5% Black, 5.1% Hispanic/Latino, and 2.6% Asian.
What is the median home value in O'Fallon, IL?
The median home value in O'Fallon is $295,700. The home-value-to-income ratio is 2.8x.
How educated is O'Fallon, Illinois?
52.4% of adults (25+) in O'Fallon hold a bachelor's degree or higher, and 23.4% hold a graduate or professional degree.