The Mackinac Bridge is a suspension bridge spanning the Straits of Mackinac to connect the non-contiguous Upper and Lower peninsulas of Michigan. Opened in 1957, the bridge (familiarly known as "Big Mac" and "Mighty Mac") is the third longest in total suspension in the world and the longest suspension bridge between anchorages in the Western hemisphere. The Mackinac Bridge carries Interstate 75 and the Lakes Michigan and Huron components of the Great Lakes Circle Tours across the straits and connects the city of St. Ignace on the north end with the village of Mackinaw City on the south.

The bridge opened on November 1, 1957, ending decades of the two peninsulas being solely linked by ferries. A year later, the bridge was formally dedicated as the "world's longest suspension bridge between anchorages." This designation was chosen because the bridge would not be the world's longest using another way of measuring suspension bridges. By saying "between anchorages", the bridge could be considered longer than the Golden Gate Bridge and also longer than the suspended western section of the San Francisco – Oakland Bay Bridge.