Mehlville is a census-designated place (CDP) in south St. Louis County, Missouri, United States, and an inner-ring suburb of St. Louis. The population was 28,380 at the 2010 census.
Mehlville is located at 38°30′15″N 90°18′46″W / 38.50417°N 90.31278°W / 38.50417; -90.31278 (38.504303, -90.312745). According to the United States Census Bureau, the CDP has a total area of 7.6 square miles (20 km), of which 7.4 square miles (19 km) is land and 0.2 square miles (0.52 km), or 2.77%, is water.
As of the census of 2000, there were 28,822 people, 12,541 households, and 7,775 families residing in the CDP. The population density was 3,913.6 people per square mile (1,512.0/km²). There were 12,982 housing units at an average density of 1,762.8/sq mi (681.0/km²). The racial makeup of the CDP was 97.08% White, 0.75% African American, 0.13% Native American, 1.77% Asian, 0.02% Pacific Islander, 0.34% from other races, and 0.61% from two or more races. Hispanic or Latino of any race were 1.45% of the population.
There were 12,541 households, out of which 25.9% had children under the age of 18 living with them, 48.6% were married couples living together, 10.2% had a female householder with no husband present, and 38.0% were non-families. 32.5% of all households were made up of individuals and 12.7% had someone living alone who was 65 years of age or older. The average household size was 2.27 and the average family size was 2.90.
In the CDP, the population was spread out, with 21.2% under the age of 18, 9.4% from 18 to 24, 28.3% from 25 to 44, 23.1% from 45 to 64, and 18.0% who were 65 years of age or older. The median age was 39 years. For every 100 females, there were 89.2 males. For every 100 females age 18 and over, there were 84.9 males.
The median income for a household in the CDP was $43,734, and the median income for a family was $55,202. Males had a median income of $41,435 versus $27,551 for females. The per capita income for the CDP was $23,125. About 3.7% of families and 5.6% of the population were below the poverty line, including 6.6% of those under age 18 and 5.4% of those age 65 or over.