Geography
Alton is located at 38°54′2″N, 90°9′35″W (38.900438, -90.159844).1 This is on the Mississippi River above the mouth of the Missouri River. Most of Alton is located on bluffs overlooking the river valley.
According to the United States Census Bureau, the city has a total area of 16.6 square miles (43.0 km²), of which, 15.6 square miles (40.5 km²) of it is land and 1.0 square miles (2.5 km²) of it (5.78%) is water.
The new Lock and Dam #26 or Melvin Prince Lock & Dam, is available for tours, and is a favorite spot to eagle watch. There is a bird sanctuary across the river.

Demographics
As of the census3 of 2000, there were 30,496 people, 12,518 households, and 7,648 families residing in the city. The population density was 1,949.3 people per square mile (752.8/km²). There were 13,894 housing units at an average density of 888.1/sq mi (343.0/km²). The racial makeup of the city was 72.32% White, 24.72% African American, 0.18% Native American, 0.38% Asian, 0.01% Pacific Islander, 0.68% from other races, and 1.71% from two or more races. Hispanic or Latino of any race were 1.49% of the population.
There were 12,518 households out of which 29.3% had children under the age of 18 living with them, 39.3% were married couples living together, 17.4% had a female householder with no husband present, and 38.9% were non-families. 33.3% of all households were made up of individuals and 13.8% had someone living alone who was 65 years of age or older. The average household size was 2.36 and the average family size was 3.02.
In the city the population was spread out with 25.8% under the age of 18, 9.1% from 18 to 24, 29.1% from 25 to 44, 20.0% from 45 to 64, and 16.0% who were 65 years of age or older. The median age was 35 years. For every 100 females there were 88.4 males. For every 100 females age 18 and over, there were 83.1 males.
The median income for a household in the city was $31,213, and the median income for a family was $37,910. Males had a median income of $33,083 versus $22,485 for females. The per capita income for the city was $16,817. About 14.7% of families and 18.7% of the population were below the poverty line, including 26.8% of those under age 18 and 13.2% of those age 65 or over.