Altus is a town in Franklin County, Arkansas, United States. It is part of the Fort Smith, Arkansas-Oklahoma Metropolitan Statistical Area. The population was 817 at the 2000 census. When the Iron Mountain Railroad laid rails up the Arkansas River Valley in the 1870s from Little Rock to the Oklahoma border at Fort Smith, Altus was the highest point on the track. In recognition of this highest railroad elevation between Little Rock and Fort Smith, the station was originally known as Summit.