| Place Name | St. Mary |
| Place Type | City |
| ZIP Code(s) | 63673 63673 |
| County | Ste Genevieve County |
| Area Code(s) | 573 |
| Timezone | Central Standard Time (CST) |
| Population (2022) | 376 |
| Population Growth Rate (2010-19) | -14.17% |
| Majority Ethnicity | White 93.18% |
| US Congressional District(s) | Missouri 8th |
| State House Districts | 116 |
| State Senate Districts | 3 |
| Race/Ethnicy | Percentage of Population (2021) |
|---|---|
| White | 93.18% |
| African American | 5.11% |
| Hispanic | 0% |
| Asian | 0% |
| Native American | 0% |
| Hawaiin/Pacific Islander | 1.7% |