As of the census of 2010, there were 807 people, 358 households, and 192 families residing in the city. The population density was. There were 416 housing units at an average density of. The racial makeup of the city was 97.3% White, 0.5% Native American, 0.2% Asian, 0.2% Pacific Islander, 0.2% from other races, and 1.5% from two or more races. Hispanic or Latino of any race were 0.4% of the population. There were 358 households, of which 20.4% had children under the age of 18 living with them, 45.8% were married couplesliving together, 5.6% had a female householder with no husband present, 2.2% had a male householder with no wife present, and 46.4% were non-families. 40.8% of all households were made up of individuals, and 21.7% had someone living alone who was 65 years of age or older. The average household size was 2.01 and the average family size was 2.74. The median age in the city was 53.4 years. 17.3% of residents were under the age of 18; 4.1% were between the ages of 18 and 24; 18% were from 25 to 44; 26.3% were from 45 to 64; and 34.2% were 65 years of age or older. The gender makeup of the city was 46.2% male and 53.8% female.
2000 census
As of the census of 2000, there were 865 people, 369 households, and 221 families residing in the city. The population density was 831.2 people per square mile. There were 405 housing units at an average density of 389.2 per square mile. The racial makeup of the city was 99.42% White, 0.23% Native American, and 0.35% from two or more races. There were 369 households, out of which 22.5% had children under the age of 18 living with them, 54.5% were married couples living together, 4.3% had a female householder with no husband present, and 40.1% were non-families. 37.9% of all households were made up of individuals, and 23.6% had someone living alone who was 65 years of age or older. The average household size was 2.08 and the average family size was 2.77. In the city, the population was spread out, with 17.9% under the age of 18, 4.3% from 18 to 24, 19.2% from 25 to 44, 19.7% from 45 to 64, and 39.0% who were 65 years of age or older. The median age was 52 years. For every 100 females, there were 86.0 males. For every 100 females age 18 and over, there were 85.9 males. The median income for a household in the city was $27,688, and the median income for a family was $32,368. Males had a median income of $24,444 versus $16,513 for females. The per capita income for the city was $16,258. About 4.4% of families and 8.3% of the population were below the poverty line, including 10.8% of those under age 18 and 12.3% of those age 65 or over.
Education
Glen Ullin currently operates a K-12 school located on the bypass on the south end of Glen Ullin. Glen Ullin's school mascot is the "Bearcat". The school's nickname was previously the "Rattlers", until the school combined with Hebronhigh school and a name change took place. Glen Ullin's 1st co-op with Hebron, for football, had the team name of the "Bandits". Glen Ullin is currently combined in football with New Salem.
Notable people
Ivan Dmitri,, artist and photographer, lived in Glen Ullin from 1914 to 1918
Andrew Schirado, Delvin Greff, Mitchell Bettenhausen, Dallas Schaaf, established and competitive drivers in the demolition derby world, all from Glen Ullin.
