How old are the homes in O'Fallon, MO?

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

9.2% (±1.4 points) of the homes in O'Fallon, MO were built before 1980 (2020–2024 American Community Survey).

0.8% were built before 1940.

19.5% were built in 2010 or later.

Figures last updated on November 12, 2026.

Built before 1980: 9.2% (±1.4 points)
Built before 1940: 0.8%
Built 2010 or later: 19.5%

When the homes in O'Fallon were built

Housing units by year structure built, 2020–2024
Year built	O'Fallon	St. Charles County	Missouri	United States
2020 or later	3.7% (±0.7 points)	3.3%	1.6%	2.0%
2010 to 2019	15.8% (±1.4 points)	14.4%	8.0%	9.4%
2000 to 2009	30.2% (±2.0 points)	21.2%	13.0%	13.6%
1990 to 1999	31.4% (±1.8 points)	19.5%	12.8%	12.4%
1980 to 1989	9.6% (±1.4 points)	16.9%	11.8%	12.9%
1970 to 1979	3.1% (±0.8 points)	11.8%	14.4%	14.2%
1960 to 1969	3.2% (±0.9 points)	6.2%	11.0%	9.9%
1950 to 1959	1.8% (±0.5 points)	3.8%	9.8%	9.5%
1940 to 1949	0.3% (±0.3 points)	0.8%	4.3%	4.4%
1939 or earlier	0.8% (±0.3 points)	2.2%	13.3%	11.7%

In O'Fallon, the share of homes built before 1980 is lower than in St. Charles County (24.8%).

It is also lower than in Missouri (52.8%).

It is lower than the national figure (49.7%).

In St. Charles County, O'Fallon ranks 14 of 17 places with a published estimate, from highest to lowest share of homes built before 1980.

Statewide, it ranks 1230 of 1,247.

Rankings use the estimates alone; where margins of error overlap, neighboring ranks may not truly differ.

Why the age of a home matters: lead-based paint

Federal law treats housing built before 1978 as likely to contain lead-based paint.

Before a lease or sale of most pre-1978 housing, the landlord or seller must disclose any known lead-based paint and hazards and give the tenant or buyer the EPA pamphlet (42 U.S.C. § 4852d; 40 CFR part 745, subpart F; 24 CFR part 35, subpart A).

A contractor paid to renovate, repair or paint a pre-1978 home must be a certified firm, use a certified renovator and follow lead-safe work practices under the Renovation, Repair and Painting Rule (40 CFR part 745, subpart E) whenever the job disturbs more than 6 square feet of painted surface in a room or more than 20 square feet outside; window replacement and demolition always count (40 CFR 745.83).

Certification comes from EPA, or from the state where EPA has authorized the state to run the program.

The Census Bureau groups construction by decade, so the share built before 1978 lies between the share built before 1970 (6.1%) and the share built before 1980 (9.2%).

Homes built before 1980 in places near O'Fallon

Nearest places with a published estimate, compared with O'Fallon
Place	Distance	Homes built before 1980	Compared with this place
O'Fallon	—	9.2% (±1.4 points)	—
Dardenne Prairie	3.0 mi	3.5% (±2.4 points)	Lower
Lake St. Louis	3.5 mi	19.4% (±4.3 points)	Higher
Cottleville	4.1 mi	1.8% (±2.9 points)	Lower
St. Paul	4.6 mi	13.1% (±5.1 points)	Not measurably different
Josephville	4.8 mi	43.3% (±26.5 points)	Higher
Weldon Spring Heights	5.9 mi	92.7% (±74.8 points)	Higher
St. Peters	6.2 mi	25.2% (±2.2 points)	Higher
Weldon Spring	6.4 mi	4.0% (±3.5 points)	Lower

Nearby places with a measurably lower figure: Dardenne Prairie, MO (3.5%), Cottleville, MO (1.8%), Weldon Spring, MO (4.0%).

Nearby places with a measurably higher figure: Lake St. Louis, MO (19.4%), Josephville, MO (43.3%), Weldon Spring Heights, MO (92.7%).

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

Homes built before 1980 across St. Charles County, place by place

Rank	Place	Homes built before 1980
8	Lake St. Louis	19.4% (±4.3 points)
9	Flint Hill	18.0% (±13.4 points)
10	New Melle	16.0% (±26.1 points)
11	St. Paul	13.1% (±5.1 points)
12	Foristell	11.4% (±11.5 points)
13	Wentzville	9.8% (±2.5 points)
14	O'Fallon	9.2% (±1.4 points)
15	Weldon Spring	4.0% (±3.5 points)
16	Dardenne Prairie	3.5% (±2.4 points)
17	Cottleville	1.8% (±2.9 points)

Showing 10 of 17 places in St. Charles 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 old are most homes in O'Fallon?

9.2% of homes in O'Fallon, MO were built before 1980 (2020–2024 American Community Survey).

Do homes in O'Fallon need a lead paint disclosure?

A home built before 1978 does, before it is rented or sold, unless an exemption applies (42 U.S.C. § 4852d); between 6.1% and 9.2% of homes in O'Fallon were built before then.

Does a contractor need lead certification to work on older homes in O'Fallon?

Yes, when the job disturbs more than 6 square feet of paint in a room or 20 square feet outside, or replaces a window: the firm must be certified and a certified renovator must direct the work under the Renovation, Repair and Painting Rule (40 CFR part 745, subpart E).

Sources

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

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, Missouri (place:54074, in state:29).

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_0017PE, DP04_0017PM, DP04_0018PE, DP04_0018PM, DP04_0019PE, DP04_0019PM, DP04_0020PE, DP04_0020PM, DP04_0021PE, DP04_0021PM, DP04_0022PE, DP04_0022PM, DP04_0023PE, DP04_0023PM, DP04_0024PE, DP04_0024PM, DP04_0025PE, DP04_0025PM, DP04_0026PE, DP04_0026PM

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.