St. Peters: Demographics & People
59,092 people call St. Peters home, in 24,591 households. Population grew 1.5% from 58,200 (2022) to 59,092 (2024). Median age 41.0 years. (1.2y older than St. Charles County; 1.8y older than Missouri). Children under 18 are 21% of the population. Population is 85% White (non-Hispanic) and 5% Black. The community is somewhat diverse (Simpson index 0.20). 62% of households are family-led. County is gaining 5,845 residents per year (2022-2023). County health: 36% adult obesity, 16% smoke.
- 2.4 people per household.
- 38% non-family households (singles, roommates).
Population & Trend
Population grew 1.5% from 58,200 (2022) to 59,092 (2024) — about 2.6× the recent U.S. annual rate of ~0.6%/yr. Estimated 2026 population: ~59,999 (extrapolated at 0.8%/yr trend). Census Bureau Vintage estimate: 61,221.
| Census data vintage | 2024 |
|---|---|
| Population | 405,262 people |
| Annual growth rate · Population change | 1.5% |
| Annual growth rate · Population (2022) | 58,200 |
| Annual growth rate · Population (2024) | 59,092 |
| Annual growth rate · Population growing | Yes |
| Annual growth rate · Trend category | growing |
| Population | 59,092 people |
| Population Estimate | 61,221 |
Sources: Census ACS 5-Year 2023, Table B01003 · Refreshed 2026-04-12
Age Distribution
Median age 41.0y is 2.1 years older than the U.S. median (38.9y). Children under 18 make up 21% — below the U.S. share of ~22%.
| Age Summary · Median age | 41.0 years (vs Missouri 39.2y) |
|---|---|
| Age Summary · Children Pct | 20.9% |
| Age Summary · Character | established |
| Population under 18 | 12,344 |
| Median age | 41.0 years (vs Missouri 39.2y) |
Sources: Census ACS 5-Year 2023 · Refreshed 2026-04-12
Race, Ethnicity & Diversity
Of 59,092 residents, race / ethnicity breaks down by Census ACS counts (a person can identify with one or more groups). The Simpson diversity index is 0.20 (0 = single group, 1 = perfectly even distribution); this is read as somewhat diverse.
| White residents | 49,929 |
|---|---|
| Black residents | 3,120 |
| Asian residents | 1,403 |
| Hispanic or Latino residents | 1,612 |
| Diversity Index · Diversity index (Simpson) | 20.2% |
| Diversity Index · Diversity label | somewhat diverse |
| Diversity Index · Groups counted | 4 |
| Diversity Index · Largest group share | 89.1% |
| Asian population | 2.6% |
| Black population | 4.6% |
| Hispanic or Latino population | 2.9% |
| White (non-Hispanic) population | 85.0% |
Sources: Census ACS 5-Year 2023 · Refreshed 2026-04-12
Ancestry
Self-reported ancestry from Census ACS — what residents report as their ethnic origin, separate from race. Counts can exceed population because people can list multiple ancestries.
Top (8)
Citizenship & Origin
Where residents were born and their citizenship status (Census ACS). 0.8% are foreign-born — below the U.S. average of 13.9%. 4% have naturalized to U.S. citizenship.
| Residents born in this state | 42,073 |
|---|---|
| Residents born in another state | 14,321 |
| Share born in this state | 71.2% |
| Share born in another state | 28.8% |
| Native-born U.S. citizens | 24.2% |
| Foreign-born residents | 0.8% |
| Naturalized citizens | 3.8% |
| Total foreign-born residents | 1,786 |
| From Europe | 340 |
| From Africa | 771 |
| From Latin America | 13 |
Households & Family Composition
24,591 households. Averaging 2.4 people each — matches the U.S. average of 2.5. 62% are family households — below the U.S. share of ~65%. Of 15,215 families, 32% are married couples with children.
| Children under 18 | 12,418 |
|---|---|
| Total families | 15,215 |
| Married couples with children | 4,867 |
| Single-parent households | 564 |
| Average household size | 2.41 |
| Women who gave birth (past year) | 13.7% |
| Grandparents living with grandchildren | 574 |
| Grandparents responsible for grandchildren | 368 |
| Family households | 15,308 households |
| Households that are families | 62.3% |
| Total households | 24,591 households |
Sources: Census ACS 5-Year 2023 · Refreshed 2026-04-12
Residential Stability & Migration
How long residents have lived here and where they came from. 9.5% moved within the county in the past year — the U.S. baseline is roughly 8–10%. The surrounding county is gaining 5,845 residents per year on net (IRS migration data).
| Moved within the county (past year) | 9.5% |
|---|---|
| Migration · People moving in (annual) | 403,338 |
| Migration · People moving out (annual) | 397,493 |
| Migration · Net migration (in − out) | 5,845 |
| Migration · Population growing | Yes |
| Migration · Year | 2022-2023 |
Sources: IRS SOI Migration 2021-2022 · Refreshed 2026-04-12
Disability
Census ACS measures self-reported functional limitations — vision, hearing, mobility, cognitive, self-care, or independent-living. The U.S. baseline disability rate is about 12–13%; rates trend higher with median age.
| Residents with a disability | 3,554 |
|---|---|
| Disability rate | 6.2% |
Group Quarters
Group quarters are non-household living arrangements counted by the Census — college dormitories, nursing homes, military barracks, group homes, correctional facilities, and similar institutional or shared housing. 416 residents live in group quarters (0.7% of population).
| Living in group quarters | 416 |
|---|
Other
| Congressional District · District | 3 |
|---|---|
| Congressional District · Congress | 118th |
| Cdc Birth Rate · Fips | 29,183 |
| Cdc Birth Rate · State Fips | 29 |
| Cdc Birth Rate · County Fips | 183 |
| Cdc Birth Rate · County | St Charles |
| Cdc Birth Rate · Birth Rate | 7.0% |
| Cdc Birth Rate · Lower Ci | 6.30 |
| Cdc Birth Rate · Upper Ci | 7.80 |
| Cdc Mortality · Fips | 29,183 |
| Cdc Mortality · County | St. Charles County |
| Cdc Mortality · Urban Rural | Large fringe metro |
| Cdc Mortality · Total Deaths 2020 2023 | 11,643 |
| Cdc Vaccination · Fips | 29,183 |
| Cdc Vaccination · County | St. Charles County |
| Cdc Vaccination · Dose1 Pop Pct | 72.7% |
| Cdc Vaccination · Series Complete Pct | 64.3% |
| Cdc Vaccination · Booster Pct | 52.4% |
| Cdc Vaccination · Population 2019 | 402,022 |
| Cdc Vaccination · Metro Status | Metro |
| Family Score · Score | 1.50 |
| Family Score · Schools | 1 |
| Family Score · Children Pct | 20.9% |
| Family Score · Rating | limited |
| Town Summary · Key Facts | population 59,092, growing, established, upper-middle, white collar |
| Town Summary · Population | 59,092 people |
| Town Summary · County | St. Charles County |
Sources: NCES school congressional district assignment · federal dataset cascade