Altamont is a town in Deuel County, South Dakota, United States.

Altamont is located on State Route 15, approximately 6 miles (9.7 km) north of the city of Clear Lake.

According to the United States Census Bureau, the town has a total area of 1.25 square miles (3.24 km2), all land.

50.0% of all households were made up of individuals, and 28.6% had someone living alone who was 65 years of age or older.

31.3% of all households were made up of individuals, and 12.5% had someone living alone who was 65 years of age or older.

There were no families and 20.5% of the population living below the poverty line, including no under eighteens and 100.0% of those over 64.