Oacoma is a town in Lyman County, South Dakota, United States.

[6] Oacoma is located on the west bank of the Missouri River, across from Chamberlain.

On September 17, 1804, Lewis and Clark camped on the west bank of the Missouri River near American Island where Oacoma is now located.

During the remainder of the 19th century the area was a stopping off place for explorers, fur traders and steamboat men.

The town is located approximately halfway between Sioux Falls and Rapid City.

30.2% of all households were made up of individuals, and 9.3% had someone living alone who was 65 years of age or older.

The racial makeup of the town was 94.36% White, 3.33% Native American, and 2.31% from two or more races.