The district municipality occupies the western half of the county and its administrative seat is in the village of Sherbrooke.
Demographics
In the 2021 Census of Population conducted by Statistics Canada, the Municipality of the District of St. Mary's had a population of 2,161 living in 1,047 of its 1,538 total private dwellings, a change of -3.2% from its 2016 population of 2,233. With a land area of 1,904.08 km2 (735.17 sq mi), it had a population density of 1.1/km2 (2.9/sq mi) in 2021.[4]