Start your route about 45 miles north of Flint Michigan in the town of Bay City. From Bay City take state route 13 north until it meets US route 23 (near Standish MI). Then simply take route 23 the entire way up to East Tawas, Alpena, Cheboygan and on to Mackinac Island.
This is a great route that hugs the Lake Huron shore as it makes its way up the coast towards Upper Peninsula Michigan. Michigan is one of the more scenery-blessed states in the Midwest and this route shows you a wide variety of what the state has to offer. Not only will the scenery keep you smiling but the pretty little resort towns and impressive beachfront homes (both old and new) will also give you plenty to gawk at.