According to the United States Census Bureau, the city has a total area of 37.4 km² (14.4 mi²). 36.4 km² (14.1 mi²) of it is land and 1.0 km² (0.4 mi²) of it is water. The total area is 2.56% water.
As of the census of 2000, there are 31,542 people, 11,178 households, and 7,668 families residing in the city. The population density is 866.2/km² (2,242.9/mi²). There are 12,899 housing units at an average density of 354.2/km² (917.2/mi²). The racial makeup of the city is 1.23% White, 97.74% African American, 0.19% Native American, 0.08% Asian, 0.03% Pacific Islander, 0.19% from other races, and 0.55% from two or more races. 0.73% of the population are Hispanic or Latino of any race.
There are 11,178 households out of which 33.2% have children under the age of 18 living with them, 21.9% are married couples living together, 40.6% have a female householder with no husband present, and 31.4% are non-families. 27.8% of all households are made up of individuals and 10.4% have someone living alone who is 65 years of age or older. The average household size is 2.80 and the average family size is 3.42.
In the city the population is spread out with 32.8% under the age of 18, 9.7% from 18 to 24, 24.6% from 25 to 44, 20.3% from 45 to 64, and 12.5% who are 65 years of age or older. The median age is 31 years. For every 100 females there are 81.5 males. For every 100 females age 18 and over, there are 72.5 males.
The median income for a household in the city is $21,324, and the median income for a family is $24,567. Males have a median income of $27,864 versus $21,850 for females. The per capita income for the city is $11,169. 35.1% of the population and 31.8% of families are below the poverty line. Out of the total people living in poverty, 48.6% are under the age of 18 and 25.2% are 65 or older.
See also: Saint Louis, Missouri