Four Mile, historically called Moss City, is an unincorporated community in Custer County, South Dakota, United States, located 4 miles (6.4 km) west of Custer at the junction of U.S. Route 16 and Pleasant Valley Road (County Highway 715).

Named because of the distance from Custer on the original Sidney Black Hills Stage Road, Four Mile today is a small bedroom community for Custer, with a single tourist attraction (the Four Mile Old West Town Museum), a log-cabin manufacturer, a small mobile home court, and several other residences.

Four Mile got its start as a stockade camp for General George Armstrong Custer's army in the 1870s.

At the beginning of the 20th century, Moss City reverted to its old name of Four Mile as the population began to decline.

Today, only a few buildings from the original townsite remain; others were recreated for the 1994 opening of the Four Mile Old West Town Museum.