Alton is a city in Sioux County, Iowa, United States, along the Floyd River.

[2] Alton was originally called East Orange, and under the latter name was laid out in 1875 when the railroad was extended to that point.

[5] According to the United States Census Bureau, the city has a total area of 1.85 square miles (4.79 km2), all land.

There were 526 housing units at an average density of 276.5 per square mile (106.8/km2).

Hispanic or Latino persons of any race comprised 6.5% of the population.

There were 493 housing units at an average density of 266.5 per square mile (102.9/km2).

24.9% of all households were made up of individuals, and 12.1% had someone living alone who was 65 years of age or older.

There were 466 housing units at an average density of 312.9 per square mile (120.8/km2).

30.1% of all households were made up of individuals, and 15.7% had someone living alone who was 65 years of age or older.

Spalding Catholic School, which serves elementary grades, is located in a single campus in Alton.