Glen St. Mary or Glen Saint Mary
| source =
Demographics
2010 and 2020 census
{| class="wikitable"
|+Glen St. Mary racial composition<br> (Hispanics excluded from racial categories)<br> (NH = Non-Hispanic)<br>
!Race
!Pop 2010
!Pop 2020
!% 2010
!% 2020
|-
|White (NH)
|407
|412
|93.14%
|88.98%
|-
|Black or African American (NH)
|10
|17
|2.29%
|3.67%
|-
|Native American or Alaska Native (NH)
|2
|0
|0.46%
|0.00%
|-
|Asian (NH)
|3
|0
|0.69%
|0.00%
|-
|Pacific Islander or Native Hawaiian (NH)
|0
|0
|0.00%
|0.00%
|-
|Some other race (NH)
|0
|0
|0.00%
|0.00%
|-
|Two or more races/Multiracial (NH)
|7
|21
|1.60%
|4.54%
|-
|Hispanic or Latino (any race)
|8
|13
|1.83%
|2.81%
|-
|Total
|437
|463
|
|
|-
|}
As of the 2020 United States census, there were 463 people, 238 households, and 162 families residing in the town.
As of the 2010 United States census, there were 437 people, 203 households, and 163 families residing in the town.
2000 census
At the 2000 census,