The Detroit, Mackinac and Marquette Railroad was a land grant railroad that was built and operated briefly (1881–1886) in the Upper Peninsula of the U.S. state of Michigan. Incorporated in 1879, the 151.9-mile (244.5 km)-long railroad began operations in 1881. It was intended to help the economic development of a region of frontier timberland along the shores of Lake Michigan and Lake Superior. Its successor line was the Duluth, South Shore and Atlantic Railway.