| Place Name | St. Mary |
| Place Type | Census Designated Place |
| ZIP Code(s) | 59411 59434 |
| County | Glacier County |
| Area Code(s) | 406 |
| Timezone | Mountain Standard Time (MST) |
| Population (2022) | 579 |
| Majority Ethnicity | White 77.1% |
| US Congressional District(s) | Montana At-Large |
| State House Districts | 16 |
| State Senate Districts | 8 |
| Race/Ethnicy | Percentage of Population (2021) |
|---|---|
| White | 77.1% |
| African American | 0% |
| Hispanic | 0% |
| Asian | 0% |
| Native American | 4.7% |
| Hawaiin/Pacific Islander | 18.2% |