
St. Mary
- County:
- Glacier County
- County Seat:
- No
- Area (mi²):
- 0.753
- State:
- Montana
St. Mary is a CDP located in Glacier County, Montana. St. Mary has a 2025 population of 303. St. Mary is currently growing at a rate of 7.45% annually but its population has decreased by -47.67% since the most recent census, which recorded a population of 579 in 2020.
The average household income in St. Mary is -$1000.00 Mn with a poverty rate of 52.58%. The median age in St. Mary is 22 years: 21.6 years for males, and 24.6 years for females.