The Detroit and Mackinac Railway (reporting marks D&M, DM), informally known as the "Turtle Line", was a railroad in the northeastern part of the Lower Peninsula of the U.S. state of Michigan.

During the late 1890s and the first decade of the Twentieth Century, the timber resources of northeastern Michigan were fully utilized and the D&M expanded its trackage northward from Alpena to Cheboygan.

In 1922, the railroad also had branch lines to Au Gres, Comins, Curran, Hillman, Lincoln, Prescott, and Rose City.

However, adverse economic conditions continued to affect railroad operations in the northeastern United States.

[8] Separate motor coach trains operating daily except Sunday carried passengers from Alpena to the northern extent of D&M territory, Cheboygan.

[5] Named train passenger service in the mid-1930s consisted of:[8] The Lake State Railway continued as of 2012 to use traditional handheld technology (picks, shovels, hammers) to replace railroad ties and make other roadbed repairs on surviving trackage that had previously been part of the Detroit and Mackinac system.