 The Mackinac Bridge is part of Interstate 75 and the Lake Michigan and Huron components of the Great Lakes Circle Tour across the straits; it is also a segment of the U.S. North Country National Scenic Trail.The bridge connects the city of St. Ignace on the north end with the village of Mackinaw City on the south.Envisioned since the 1880s, the bridge was designed by the engineer David B. Steinman and completed in 1957 only after many decades of struggles to begin construction.