| Place Name | St. Martin |
| Place Type | Census Designated Place |
| ZIP Code(s) | 45107 45118 45142 |
| County | Brown County |
| Area Code(s) | 283,513 |
| Timezone | Eastern Standard Time (EST) |
| Population (2022) | 256 |
| Population Growth Rate (2010-19) | 55.04% |
| Majority Ethnicity | White 100% |
| Metro/Micro Stats Area | Cincinnati, OH-KY-IN |
| US Congressional District(s) | Ohio 2nd |
| State House Districts | 66 |
| State Senate Districts | 14 |
| Race/Ethnicy | Percentage of Population (2021) |
|---|---|
| White | 100% |
| African American | 0% |
| Hispanic | 0% |
| Asian | 0% |
| Native American | 0% |
| Hawaiin/Pacific Islander | 0% |