The Mackinac Bridge ( MAK-in-aw) is a suspension bridge spanning the Straits of Mackinac, connecting the Upper and Lower peninsulas of the U.S. state of Michigan. Opened in 1957, the 26,372-foot-long (4.995 mi; 8.038 km) bridge (familiarly known as "Big Mac" and "Mighty Mac") is the world's 26th-longest main span and the longest suspension bridge between anchorages in the Western Hemisphere. The Mackinac Bridge is part of Interstate 75 (I-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.