Erwin is a town in Kingsbury County, South Dakota, United States.

[7] James Erwin Hollister, an early postmaster, gave the town his name.

[7] According to the United States Census Bureau, the town has a total area of 0.48 square miles (1.24 km2), all land.

There were 29 housing units at an average density of 60.4 per square mile (23.3/km2).

31.8% of all households were made up of individuals, and 13.6% had someone living alone who was 65 years of age or older.

26.9% of all households were made up of individuals, and 23.1% had someone living alone who was 65 years of age or older.