St. Martin: Demographics & People
About 171 people live in St. Martin, in 80 households. Population grew 28.6% from 133 (2022) to 171 (2024). Median age 56.9 years. (14.4y older than Brown County; 17.1y older than Ohio). Children under 18 are 8% of the population. Population is 100% White (non-Hispanic). The community is relatively homogeneous (Simpson index 0.00). 66% of households are family-led. County is gaining 1,056 residents per year (2022-2023). County health: 43% adult obesity, 23% smoke.
- 2.1 people per household.
- 34% non-family households (singles, roommates).
Population & Trend
Population grew 28.6% from 133 (2022) to 171 (2024) — about 47.6× the recent U.S. annual rate of ~0.6%/yr. Estimated 2026 population: ~223 (extrapolated at 14.3%/yr trend). Census Bureau Vintage estimate: 307.
| Census data vintage | 2024 |
|---|---|
| Population | 43,676 people |
| Annual growth rate · Population change | 28.6% |
| Annual growth rate · Population (2022) | 133 |
| Annual growth rate · Population (2024) | 171 |
| Annual growth rate · Population growing | Yes |
| Annual growth rate · Trend category | booming |
| Population | 171 people |
| Population Estimate | 307 |
Sources: Census ACS 5-Year 2023, Table B01003 · Refreshed 2026-04-12
Age Distribution
Median age 56.9y is 18.0 years older than the U.S. median (38.9y). Children under 18 make up 8% — below the U.S. share of ~22%.
| Age Summary · Median age | 56.9 years (vs Ohio 39.8y) |
|---|---|
| Age Summary · Children Pct | 8.2% |
| Age Summary · Character | retirement community |
| Population under 18 | 14 |
| Median age | 56.9 years (vs Ohio 39.8y) |
Sources: Census ACS 5-Year 2023 · Refreshed 2026-04-12
Race, Ethnicity & Diversity
Of 171 residents, race / ethnicity breaks down by Census ACS counts (a person can identify with one or more groups). The Simpson diversity index is 0.00 (0 = single group, 1 = perfectly even distribution); this is read as relatively homogeneous.
| White residents | 133 |
|---|---|
| Diversity Index · Diversity label | relatively homogeneous |
| Diversity Index · Groups counted | 1 |
| Diversity Index · Largest group share | 100.0% |
| White (non-Hispanic) population | 100.0% |
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 (4)
Citizenship & Origin
Where residents were born and their citizenship status (Census ACS).
| Residents born in this state | 113 |
|---|---|
| Residents born in another state | 58 |
| Share born in this state | 66.1% |
| Share born in another state | 33.9% |
| Native-born U.S. citizens | 33.9% |
| Total foreign-born residents | 155 |
Households & Family Composition
80 households. Averaging 2.1 people each — smaller than the U.S. average of 2.5. 66% are family households — near the U.S. share of ~65%. Of 47 families, 13% are married couples with children.
| Children under 18 | 11 |
|---|---|
| Total families | 47 |
| Married couples with children | 6 |
| Average household size | 2.11 |
| Women who gave birth (past year) | 33.3% |
| Grandparents living with grandchildren | 1,096 |
| Grandparents responsible for grandchildren | 475 |
| Family households | 53 households |
| Households that are families | 66.2% |
| Total households | 80 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. 6.4% moved within the county in the past year — the U.S. baseline is roughly 8–10%. The surrounding county is gaining 1,056 residents per year on net (IRS migration data).
| Moved within the county (past year) | 6.4% |
|---|---|
| Migration · People moving in (annual) | 40,525 |
| Migration · People moving out (annual) | 39,469 |
| Migration · Net migration (in − out) | 1,056 |
| Migration · Population growing | Yes |
| Migration · Year | 2022-2023 |
Sources: IRS SOI Migration 2021-2022 · Refreshed 2026-04-12
Other
| Congressional District · District | 2 |
|---|---|
| Congressional District · Formatted | OH-02 |
| Congressional District · Congress | 118th |
| Cdc Birth Rate · Fips | 39,015 |
| Cdc Birth Rate · State Fips | 39 |
| Cdc Birth Rate · County Fips | 15 |
| Cdc Birth Rate · County | Brown |
| Cdc Birth Rate · Birth Rate | 26.7% |
| Cdc Birth Rate · Lower Ci | 22.70 |
| Cdc Birth Rate · Upper Ci | 31.10 |
| Cdc Mortality · Fips | 39,015 |
| Cdc Mortality · County | Brown County |
| Cdc Mortality · Urban Rural | Large fringe metro |
| Cdc Mortality · Total Deaths 2020 2023 | 1,323 |
| Cdc Vaccination · Fips | 39,015 |
| Cdc Vaccination · County | Brown County |
| Cdc Vaccination · Dose1 Pop Pct | 45.8% |
| Cdc Vaccination · Series Complete Pct | 42.6% |
| Cdc Vaccination · Booster Pct | 49.5% |
| Cdc Vaccination · Population 2019 | 43,432 |
| Cdc Vaccination · Metro Status | Metro |
| Family Score · Score | 8.50 |
| Family Score · Schools | 15 |
| Family Score · Children Pct | 8.2% |
| Family Score · Rating | excellent |
| Town Summary · Key Facts | population 171, booming, retirement community, middle-class, blue collar |
| Town Summary · Population | 171 people |
| Town Summary · County | Brown County |
Sources: Census place-to-CD118 crosswalk (place_fips) · federal dataset cascade