In eastern Crawford County, M-72 runs through the Au Sable State Forest and crosses the South Branch of the Au Sable River on the Wakeley Bridge. East of the river crossing, the trunkline intersects the northern terminus of M-18 before crossing into Oscoda County. M-72 continues east through Luzerne to Mio. M-72 merges with M-33 and turns north to cross the Au Sable River a second time in Mio. The highways pick up a concurrency with F-32 north of the river. The three roadways run together until F-32 turns west while M-33/M-72 continues east to Fairview. Fairview marks the northern and eastern end of the concurrency as M-33 turns north towards Atlanta, and M-72 continues easterly into Alcona County. North of Curran, M-72 merges southward with M-65 for approximately before heading due east through the Barton City and Lincoln areas to Harrisville. M-72 ends at an intersection with US 23 in Harrisville, on the shores of Lake Huron.