What kinds of homes are in O'Fallon, IL?

Name: Types of homes in O'Fallon, IL, 2020–2024
Creator: US Census Bureau
License: https://www.census.gov/data/developers/about/terms-of-service.html

O'Fallon, IL has 13,530 (±485) homes (2020–2024 American Community Survey).

That is about 856 homes per square mile of land.

66.6% are detached single-family houses.

6.0% are in buildings of two to four units.

16.3% are in buildings of five or more units.

Figures last updated on November 12, 2026.

Housing units: 13,530 (±485)
Detached houses: 66.6%
2–4 unit buildings: 6.0%
5+ unit buildings: 16.3%

Homes in O'Fallon by building size

Housing units by units in structure, 2020–2024
Building type	O'Fallon	St. Clair County	Illinois	United States
Single-family, detached	66.6% (±2.8 points)	72.1%	58.2%	61.3%
Single-family, attached (townhouse, rowhouse)	7.9% (±2.6 points)	5.2%	6.1%	6.2%
2 units	0.7% (±0.5 points)	3.3%	5.2%	3.4%
3 or 4 units	5.3% (±1.7 points)	4.4%	6.4%	4.3%
5 to 9 units	7.1% (±2.6 points)	5.3%	6.3%	4.5%
10 to 19 units	2.6% (±1.3 points)	2.3%	4.0%	4.3%
20 or more units	6.6% (±2.2 points)	2.9%	11.5%	10.3%
Mobile home	3.1% (±1.2 points)	4.4%	2.3%	5.6%
Boat, RV, van, etc.	0.1% (±0.1 points)	0.0%	0.0%	0.1%

In O'Fallon, the share of homes in buildings of five or more units is higher than in St. Clair County (10.5%).

It is also lower than in Illinois (21.8%).

It is not measurably different from the national figure (19.1%).

Homes in buildings of 5 or more units in places near O'Fallon

Nearest places with a published estimate, compared with O'Fallon
Place	Distance	Homes in buildings of 5 or more units	Compared with this place
O'Fallon	—	16.3% (±3.6 points)	—
O'Fallon Township	2.9 mi	12.5% (±3.2 points)	Not measurably different
Shiloh	3.5 mi	16.3% (±5.1 points)	Not measurably different
Caseyville Township	3.6 mi	15.8% (±3.2 points)	Not measurably different
Fairview Heights	4.8 mi	13.1% (±3.8 points)	Not measurably different
Swansea	5.1 mi	12.1% (±4.2 points)	Not measurably different
Scott AFB	5.2 mi	2.1% (±5.1 points)	Lower
Shiloh Valley Township	5.4 mi	7.3% (±2.9 points)	Lower
Lebanon	5.7 mi	17.4% (±7.3 points)	Not measurably different

Nearby places with a measurably lower figure: Scott AFB, IL (2.1%), Shiloh Valley Township, IL (7.3%).

Distance is measured in a straight line between the Census Bureau’s internal points for each place.

Homes in buildings of 5 or more units across St. Clair County, place by place

Rank	Place	Homes in buildings of 5 or more units
1	Lebanon	17.4% (±7.3 points)
2 (tie)	O'Fallon	16.3% (±3.6 points)
2 (tie)	Shiloh	16.3% (±5.1 points)
4	Caseyville Township	15.8% (±3.2 points)
5 (tie)	Brooklyn	15.2% (±18.4 points)
5 (tie)	Stites Township	15.2% (±18.4 points)
7 (tie)	East St. Louis	14.9% (±2.8 points)
7 (tie)	East St. Louis Township	14.9% (±2.8 points)

Showing 8 of 46 places in St. Clair County, ranked from highest to lowest.

Survey years: 2020–2024 (American Community Survey 5-year estimates).

Margins of error are at the 90% confidence level.

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Questions about O'Fallon

How many homes are in O'Fallon?

O'Fallon, IL has an estimated 13,530 (±485) housing units, occupied and vacant (2020–2024 American Community Survey).

Are most homes in O'Fallon houses or apartments?

66.6% are detached houses and 7.9% attached houses, while 22.3% are in buildings of two or more units.

How many two-family and small multifamily homes are in O'Fallon?

6.0% of homes in O'Fallon are in buildings of two to four units, the small rental buildings that are often owner-occupied.

Sources

Selected Housing Characteristics (DP04), 2020–2024 ACS 5-year estimates — O'Fallon city, Illinois

To check these figures in the Census Bureau’s own API, request the variables below from the 2024 ACS 5-year data profile (acs/acs5/profile) for O'Fallon city, Illinois (place:55249, in state:17).

Each estimate (E or PE) has a margin of error beside it (M or PM).

The API needs a free key.

Request a Census API key.

DP04_0001E, DP04_0001M, DP04_0007PE, DP04_0007PM, DP04_0008PE, DP04_0008PM, DP04_0009PE, DP04_0009PM, DP04_0010PE, DP04_0010PM, DP04_0011PE, DP04_0011PM, DP04_0012PE, DP04_0012PM, DP04_0013PE, DP04_0013PM, DP04_0014PE, DP04_0014PM, DP04_0015PE, DP04_0015PM

This product uses the Census Bureau Data API but is not endorsed or certified by the Census Bureau.

Figures are published by the US Census Bureau, HUD, the Bureau of Labor Statistics and the FBI; Seayora reproduces them and does not adjust them, except where a sentence says it compares dollar figures after inflation. They describe the whole place, not any one building or street, and are not an appraisal, a rent determination, a tax bill, a safety rating or legal advice.