O'Fallon, Illinois Population 2026
Updated April 2026 · US Census ACS 2023 5-Year Estimates
The population of O'Fallon, Illinois is 32,139 as of the 2023 American Community Survey, making it the 58th-largest city in Illinois. The median household income is $102,793, the median home value is $274,100, and the median age is 36.9.
The population has grown 11.7% since 2010 (28,797 → 32,169).
32,139
Population
2033
People / sq mi
$102,793
Median Income
$274,100
Median Home Value
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O'Fallon covers 15.8 sq mi of land at 2033 people per square mile.
About O'Fallon, IL
O'Fallon is distinguished by its share of foreign-born residents, 48.1% of the population. With 32,139 residents, O'Fallon is a city in Illinois.
Households take in a median $102,793, comfortably above the US median of $78,538. The poverty rate, 3.1%, is on the lower side for US cities and below the national 12.4%. Homes carry a median value of $274,100, with typical rent around $1,312.
About 51.3% of adults 25 and older have a bachelor’s degree, above the 35.0% national figure. About 16.7% of workers primarily work from home, above the national 14.0%, and the average commute runs about 26 minutes each way.
The large foreign-born share is a defining thread in O'Fallon, shaping language, household composition, and the labor force behind the economic figures above.
O'Fallon city Population History (2010-2024)
The city of O'Fallon city had a population of 28,797 in 2010 and 32,169 in 2024, a 11.7% growth over 14 years. The peak was 32,413 in 2020. Average annual growth rate: 0.82%.
32,169
Population (2024)
28,797
Population (2010)
32,413
Peak (2020)
0.82%
Avg Annual Growth
| Year | Population |
|---|---|
| 2010 | 28,797 |
| 2011 | 29,407 |
| 2012 | 29,311 |
| 2013 | 29,199 |
| 2014 | 29,128 |
| 2015 | 29,098 |
| 2016 | 29,153 |
| 2017 | 29,320 |
| 2018 | 29,557 |
| 2019 | 29,583 |
| 2020 | 32,413 |
| 2021 | 32,389 |
| 2022 | 32,247 |
| 2023 | 32,186 |
| 2024 | 32,169 |
Race & Ethnicity
| White | 72.6% |
| Black or African American | 13.6% |
| Asian | 0.0% |
| Hispanic or Latino (any race) | 2.5% |
| Two or More Races | 0.0% |
Economy & Income
$102,793
Median Household Income
$51,826
Per Capita Income
3.1%
Poverty Rate
2.1%
Unemployment Rate
Housing
$274,100
Median Home Value
$1,312
Median Rent
70.9%
Owner-Occupied
Education
96.9%
High School+
51.3%
Bachelor's+
Commute
0.4%
Drive Alone
75.2%
Public Transit
16.7%
Work From Home
26.1 min
Avg Commute
Community Profile
48.1%
Foreign Born
92.9%
Non-English at Home
19.4%
Veterans
10.5%
With Disability
95.7%
Health Insurance
97.8%
Internet Access
Employment by Industry
| Professional, Scientific & Management | 24.7% |
| Finance, Insurance & Real Estate | 16.0% |
| Public Administration | 10.4% |
| Information | 8.1% |
| Education, Health Care & Social Services | 7.8% |
| Retail Trade | 7.4% |
| Manufacturing | 6.5% |
| Arts, Entertainment & Food Services | 3.4% |
| Construction | 3.4% |
| Transportation & Warehousing | 1.2% |
| Agriculture & Mining | 0.4% |
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Frequently Asked Questions
O'Fallon, Illinois has a population of 32,139 according to the US Census Bureau's 2023 American Community Survey 5-year estimates, making it the 58th-largest city in Illinois.
The median household income in O'Fallon, Illinois is $102,793, with 3.1% of residents living below the federal poverty level.
The median home value in O'Fallon, Illinois is $274,100, with median monthly rent at $1,312 and a homeownership rate of 70.9%.
The median age in O'Fallon, Illinois is 36.9 years. The population is 49.4% male and 50.6% female.
The population has grown 11.7% since 2010 (28,797 → 32,169).
O'Fallon city, IL Climate
O'Fallon city, IL has an average annual temperature of 12.6°C (55°F) and receives about 964 mm of precipitation per year. The warmest month is July and the coldest is January. Figures are 1970–2000 climate normals.
12.6°C
Avg Temp
964
Precip (mm/yr)
Jul
Hottest Month
Jan
Coldest Month
| Month | Avg (°C/°F) | Precip |
|---|---|---|
| January | -2° / 28° | 51 mm |
| February | 1° / 33° | 58 mm |
| March | 7° / 44° | 87 mm |
| April | 13° / 55° | 95 mm |
| May | 18° / 65° | 103 mm |
| June | 23° / 74° | 96 mm |
| July | 26° / 78° | 92 mm |
| August | 24° / 76° | 81 mm |
| September | 20° / 69° | 82 mm |
| October | 14° / 57° | 68 mm |
| November | 7° / 45° | 78 mm |
| December | 1° / 34° | 73 mm |
1970–2000 normals from WorldClim 2.1 (~9 km grid). Precipitation can be less precise near mountains or coastlines, where rainfall varies sharply over short distances.
Best time to visit O'Fallon city, IL
The most comfortable months to visit O'Fallon city, IL are typically September, June and August, when temperatures are mildest and rainfall is relatively low. The hottest month is July (around 31°C high). The coldest is January (near -7°C low). May is usually the wettest month.
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Data from the American Community Survey (ACS) 5-Year estimates.
Source: U.S. Census Bureau ACS, 2026.