Mount Vernon is a city in and the county seat of Jefferson County, Illinois, United States. The population was 15,277 at the 2010 census.
According to the 2010 census, Mount Vernon has a total area of 13.151 square miles (34.06 km), of which 13.07 square miles (33.85 km) (or 99.38%) is land and 0.081 square miles (0.21 km) (or 0.62%) is water.
The community is about 80 miles (130 km) east of St. Louis, Missouri.
Mt. Vernon is located on high ground between Casey Creek and the Big Muddy River, which join south of the town in what is now Rend Lake. In pre-settlement times the area around these waterways was a swamp, a heavily forested area that was waist-deep in water during much of the winter and during wet summers. Mt. Vernon was thus often surrounded by water and swamp on three sides.
High ground was located to the north of Mt. Vernon. A ridge ran between the Big Muddy River and Casey Creek north toward what is now Dix.
There are high places both west and east of Mt. Vernon from which one can see the town as a forested point of high ground jutting out into the bottoms. These high places are: from the west, near the Woodlawn interchange off Interstate 64 and from the east, on Old Fairfield Road near Summersville School, with the highest point located on Old Route 15 right before it merges with New Route 15, near Bluford.
As of the census of 2010, there were 15,277 people, 6,702 households and 3,781 families residing in the city. The population density was 1,168.7 people per square mile (545.3/km²). There were 7,534 housing units. The racial makeup of the city was 80.6% White, 14.7% African American, 0.3% Native American, 1% Asian, 0.0% Pacific Islander, and 2.6% from two or more races. Hispanic or Latino of any race were 2.4% of the population.
There were 6,702 households out of which 25.8% had children under the age of 18 living with them, 35% of all households were married couples living together, 16.3% had a female householder with no husband present, and 43.6% were non-families. 37.6% of all households were made up of individuals and 16.1% had someone living alone who was 65 years of age or older. The average household size was 2.23 and the average family size was 2.92.
In the city the population was spread out with 24.3% under the age of 18, 6.2% from 20 to 24, and 18% who were 65 years of age or older. The median age was 38.3 years. Males represent 46.5% of the population, and 34% of the population was male and over 18. Women were 53.5% of the population, 41% of the population being female and over 18.
The median income for a household in the city was $32,549, and the median income for a family was $36,660. Males had a median income of $28,324 versus $16,497 for females. The per capita income for the city was $21,283. About 19.9% of families and 23.7% of the population were below the poverty line, including 35.4% of those under age 18 and 11.7% of that age 65 or over. 53.9% of households earn less than $35,000.
Of the population over age 25, 72.7% have no college degree. 13.6% of those over 25 have no high school diploma nor equivalent. 7.6% of the population has a bachelor’s degree or higher.
According to the US Census, health care services and social services employ the second most people with 1,001 estimated jobs. Accommodation and food services (restaurants) are the highest employer with 1,146 estimated jobs.
Mount Vernon Illinois neighborhoods include: Bethel, Country Rd 1535 N, Downtown, Summersville