M-33 follows Morenci Avenue into the center of Mio where the highway joins M-72 south of Mio Pond, and they run concurrently together across the Mio Pond section of the Au Sable River out of town. On the north side of the river, F-32 merges in from the east and the three roadway designations run concurrently north. The highway continues to a sweeping 90° turn east near Smith Lake. F-32 separates to turn west and M-33/M-72 turns eastward. The trunkline continues to Fairview where M-33 turns north, leaving the M-72 concurrency to continue northward. M-33 crosses into the Mackinaw State Forest and passes through Comins. North of that unincorporated community, the highway curves northeast, east and back north to cross into Montmorency County. Before reaching M-32, M-33 crosses the Thunder Bay River. After the river, M-33 turns westward along M-32 to the community of Atlanta. The highway passes near the Atlanta Municipal Airport as it enters the community. In the middle of town, M-33 turns back north. The highway provides access to the Clear Lake State Park in northern Montmorency County before crossing into Presque Isle County.
