St. Charles County: Demographics & People
About 414,535 people live in St. Charles County. Median age 39.8 years. (0.6y older than Missouri). Population is 5% Black and 4% Hispanic or Latino. County is gaining 5,845 residents per year (2022-2023). County health: 37% adult obesity, 13% smoke.
Population & Trend
Current population 414,535; figures track the most recent Census ACS 5-year estimates.
| Population | 414,535 people |
|---|---|
| Total Town Population | 311,105 people |
Age Distribution
Median age 39.8y is 0.9 years older than the U.S. median (38.9y).
| Age Summary · Total Pop | 414,535 |
|---|---|
| Age Summary · Under 18 | 93,380 |
| Age Summary · 18 To 34 | 85,079.0× |
| Age Summary · 35 To 64 | 165,668.0× |
| Age Summary · 65 Plus | 70,408 |
| Age Summary · Pct Under 18 | 22.5% |
| Age Summary · Pct 18 To 34 | 20.5% |
| Age Summary · Pct 35 To 64 | 40.0% |
| Median age | 39.8 years (vs Missouri 39.2y) |
Sources: Census ACS 5-Year 2024 — county-level query · Refreshed 2026-04-28
Race, Ethnicity & Diversity
Of 414,535 residents, race / ethnicity breaks down by Census ACS counts (a person can identify with one or more groups).
| Census Demographics · Total Population | 414,535 people |
|---|---|
| White residents | 348,354 |
| Black residents | 21,335 |
| Asian residents | 12,632 |
| Census Demographics · Aian | 333 |
| Census Demographics · Nhpi | 187 |
| Census Demographics · Other Race | 5,181 |
| Census Demographics · Two Or More Races | 26,513 |
| Diversity Index | 28.6% |
| Asian population | 3.0% |
| Black population | 5.2% |
| Hispanic or Latino population | 4.2% |
Sources: Census ACS 5-Year 2024 — county-level query · Refreshed 2026-04-28
Citizenship & Origin
Where residents were born and their citizenship status (Census ACS).
| Census Citizenship · Total | 414,535 |
|---|---|
| Census Citizenship · Native | 396,031 |
| Residents born in this state | 284,661 |
| Residents born in another state | 107,375 |
| Census Citizenship · Foreign Born | 27,014 |
| Census Citizenship · Naturalized | 16,270 |
| Census Citizenship · Non Citizen | 3,995 |
| Foreign-born residents | 6.5% |
Sources: Census ACS 5-Year 2024 — county-level query · Refreshed 2026-04-28
Residential Stability & Migration
How long residents have lived here and where they came from. The surrounding county is gaining 5,845 residents per year on net (IRS migration data).
| 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 2022-2023
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.
| Census Disability · Total Pop | 412,563 |
|---|---|
| With Disability | 48,384 |
| Pct With Disability | 11.7% |
Sources: Census ACS 5-Year 2024 — county-level query · Refreshed 2026-04-28
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. 0 residents live in group quarters.
| Census Group Quarters · Total | 6,246 |
|---|
Sources: Census ACS 5-Year 2024 — county-level query · Refreshed 2026-04-28
Other
| Census Mobility · Total | 410,297 |
|---|---|
| Census Mobility · Same House | 367,453 |
| Census Mobility · Same County | 19,768 |
| Census Mobility · Diff County Same State | 13,689 |
| Census Mobility · Diff State | 7,685 |
| Census Mobility · From Abroad | 1,702 |
| Census Mobility · Moved Total | 42,844 |
| Census Mobility · Pct Moved In Year | 10.4% |
| Pct White | 84.0% |
Sources: Census ACS 5-Year 2024 — county-level query · Refreshed 2026-04-28