2020 census

As of the 2020 census, Mount Vernon had a population of 1,354.^[8] The median age was 44.8 years. 22.1% of residents were under the age of 18 and 21.3% of residents were 65 years of age or older. For every 100 females there were 92.3 males, and for every 100 females age 18 and over there were 87.1 males age 18 and over.^[9]

0.0% of residents lived in urban areas, while 100.0% lived in rural areas.^[10]

There were 540 households in Mount Vernon, including 336 families, and 32.2% of households had children under the age of 18 living in them. Of all households, 33.9% were married-couple households, 21.7% were households with a male householder and no spouse or partner present, and 40.7% were households with a female householder and no spouse or partner present. About 31.7% of all households were made up of individuals and 15.0% had someone living alone who was 65 years of age or older.^[9]

There were 634 housing units, of which 14.8% were vacant. The homeowner vacancy rate was 0.7% and the rental vacancy rate was 5.5%.^[9]

2010 census

At the 2010 census there were 1,574 people, 556 households, and 399 families in the town. The population density was 828.4 inhabitants per square mile (319.8/km²). There were 667 housing units at an average density of 351.1 per square mile (135.6/km²). The racial makeup of the town was 73.6% Black or African American, 23.4% White, 1.7% Native American, 0.1% from other races, and 1.1% from two or more races. 0.7% of the population were Hispanic or Latino of any race.^[11] Of the 556 households 26.4% had children under the age of 18 living with them, 45.5% were married couples living together, 21.8% had a female householder with no husband present, and 28.2% were non-families. 25.4% of households were one person and 10.2% were one person aged 65 or older. The average household size was 2.72 and the average family size was 3.31.

The age distribution was 23.9% under the age of 18, 8.9% from 18 to 24, 19.9% from 25 to 44, 32.3% from 45 to 64, and 14.9% 65 or older. The median age was 42.3 years. For every 100 females, there were 97.7 males. For every 100 females age 18 and over, there were 101.9 males.

The median household income was $34,722 and the median family income was $46,111. Males had a median income of $41,250 versus $23,625 for females. The per capita income for the town was $13,790. About 2.7% of families and 26.5% of the population were below the poverty line, including 1.7% of those under age 18 and 18.9% of those age 65 or over.

2000 census

At the 2000 census there were 844 people, 333 households, and 228 families in the town. The population density was 446.4 inhabitants per square mile (172.4/km²). There were 395 housing units at an average density of 208.9 per square mile (80.7/km²). The racial makeup of the town was 45.38% White, 52.96% Black or African American, 0.95% Native American, 0.24% from other races, and 0.47% from two or more races. 0.12% of the population were Hispanic or Latino of any race.^[12] Of the 333 households 28.8% had children under the age of 18 living with them, 50.8% were married couples living together, 14.4% had a female householder with no husband present, and 31.5% were non-families. 30.0% of households were one person and 16.2% were one person aged 65 or older. The average household size was 2.53 and the average family size was 3.19.

The age distribution was 26.2% under the age of 18, 8.6% from 18 to 24, 26.1% from 25 to 44, 22.4% from 45 to 64, and 16.7% 65 or older. The median age was 38 years. For every 100 females, there were 87.1 males. For every 100 females age 18 and over, there were 81.1 males.

The median household income was $29,861 and the median family income was $36,786. Males had a median income of $30,347 versus $18,750 for females. The per capita income for the town was $12,551. About 19.8% of families and 22.8% of the population were below the poverty line, including 32.9% of those under age 18 and 21.1% of those age 65 or over.