South Prairie is a town in Pierce County, Washington, United States.

It was named because of its location, south of Connell's and Porter's prairies.

There were 174 housing units at an average density of 446.2 per square mile (172.3/km2).

24.7% of all households were made up of individuals, and 8.4% had someone living alone who was 65 years of age or older.

There were 138 housing units at an average density of 339.0 per square mile (130.0/km2).

12.0% of all households were made up of individuals, and 3.2% had someone living alone who was 65 years of age or older.