Alton is the county seat of Oregon County, Missouri, United States. The population was 668 at the 2000 census.
Alton is located at 36°41′38″N 91°23′57″W / 36.69389°N 91.39917°W / 36.69389; -91.39917 (36.693920, -91.399076). According to the United States Census Bureau, the city has a total area of 0.8 square miles (2.2 km²), all of it land.
As of the census of 2000, there were 668 people, 321 households, and 188 families residing in the city. The population density was 797.2 people per square mile (307.0/km²). There were 364 housing units at an average density of 434.4 per square mile (167.3/km²). The racial makeup of the city was 97.01% White, 0.30% African American, 1.95% Native American, and 0.75% from two or more races. Hispanic or Latino of any race were 0.60% of the population.