M-72 starts its trans-peninsular journey at M-22 in the community of Empire on the shores of Lake Michigan in the Sleeping Bear Dunes National Lakeshore. From there it runs easterly uphill through mixed farmland and forest to cross the base of the Leelanau Peninsula. As the highway approaches the city of Traverse City, the roadway runs downhill and weaves back and forth across the Leelanau – Grand Traverse county line. M-72 merges with M-22 to run concurrently in the section of Traverse City in Leelanau County and immediately cross the county line into Grand Traverse County. The two highways run along Grandview Parkway, a four-lane boulevard on the shore of the West Arm of Grand Traverse Bay. At the intersection of Grandview Parkway and Division Street, M-22 ends. US 31/M-37 run north along Division Street and turn east onto Grandview Parkway to join M-72. These three highways stay merged in a triple concurrency along the length of Grandview Parkway and across the Boardman River along the bay, bypassing downtown. They then follow Front Street until reaching Garfield Avenue east of downtown. At Garfield, M-37 turns north to run up the Old Mission Peninsula which separates the west and east arms of Grand Traverse Bay. US 31/M-72 continues east along the shores of the East Arm of Grand Traverse Bay and northward to a junction in Acme. M-72 turns east to cross rural eastern Grand Traverse County along rolling hills through the communities of Williamsburg and Barker Creek.