Jennings is a city in St. Louis County, Missouri, United States. The population was 14,712 at the 2010 census.
Jennings is located at 38°43′16″N 90°15′41″W (38.721100, -90.261428).
According to the United States Census Bureau, the city has a total area of 3.70 square miles (9.58 km2), all land.
At the 2010 census there were 14,712 people, 5,847 households and 3,782 families living in the city. The population density was 3,976.2 per square mile (1,535.2/km2). There were 6,937 housing units at an average density of 1,874.9 per square mile (723.9/km2). The racial makeup of the city was 89.8% African American, 8.5% White, 0.1% Native American, 0.2% Asian, 0.2% from other races, and 1.1% from two or more races. Hispanic or Latino of any race were 0.6%.
Of the 5,847 households, 36.4% had children under the age of 18 living with them, 22.4% were married couples living together, 36.0% had a female householder with no husband present, 6.3% had a male householder with no wife present, and 35.3% were non-families. 31.2% of households were one person and 10.4% were one person aged 65 or older. The average household size was 2.51 and the average family size was 3.13.