Rapid River is an unincorporated community in Masonville Township, Delta County in the U.S. state of Michigan.
It is situated on the northern end of the Little Bay de Noc at 45°55′37″N 86°58′01″W / 45.92694°N 86.96694°W, between the mouths of the Tacoosh and Rapid rivers with the mouth of the Whitefish River just to the east. U.S. Highway 2 passes through Rapid River and joins with U.S. Highway 41 just west of town; the two then run concurrently from Rapid River south to Escanaba. The Rapid River ZIP code is 49878 and also serves areas in the nearby townships in Delta County of Baldwin, Bay de Noc, Brampton, Ensign, Garden, Maple Ridge, Masonville, and Nahma. It also serves a small area in Mathias Township in Alger County