Mackinac Bridge

The Mackinac Bridge (/ˈmækənɔː/ MAK-ə-naw; also referred to as the Mighty Mac or Big Mac) is a suspension bridge that connects the Upper and Lower peninsulas of the U.S. state of Michigan. It spans the Straits of Mackinac, a body of water connecting Lake Michigan and Lake Huron, two of the Great Lakes. Opened in 1957, the 26,372-foot-long (4.995 mi; 8.038 km) bridge is the world's 29th-longest main span and is the longest suspension bridge between anchorages in the Western Hemisphere. The Mackinac Bridge is part of Interstate 75 (I-75) and carries 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 to the north with the village of Mackinaw City to 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. The bridge has since become an iconic symbol of the state of Michigan.

The bridge opened on November 1, 1957, connecting two peninsulas linked for decades by ferries. At the time, the bridge was formally dedicated as the "world's longest suspension bridge between anchorages", allowing a superlative comparison to the Golden Gate Bridge, which has a longer center span between towers, and the San Francisco–Oakland Bay Bridge, which has an anchorage in the middle.

It remains the longest suspension bridge with two towers between anchorages in the Western Hemisphere. Much longer anchorage-to-anchorage spans have been built in the Eastern Hemisphere, including the Akashi Kaikyō Bridge in Japan (6,532 ft or 1,991 m), but the long leadups to the anchorages on the Mackinac make its total shoreline-to-shoreline length of 26,372 feet (8,038 m)—28 feet (8.5 m) short of five miles (8.0 km)—longer than the Akashi Kaikyo (2.4 mi or 3.9 km).

The length of the bridge's main span is 3,800 feet (1,158 m), which makes it the third-longest suspension span in the United States and 29th longest suspension span worldwide. It is also one of the world's longest bridges overall.

The Algonquian peoples who lived in the straits area prior to the arrival of Europeans in the 17th century called this region Michilimackinac, which is widely understood to mean Place of the Great Turtle. This is thought to refer to the shape of what is now called Mackinac Island. This interpretation of the word is debated by scholars. Trading posts at the Straits of Mackinac attracted peak populations during the summer trading season; they also developed as intertribal meeting places.

As usage of the state's mineral and timber resources increased during the 19th century, the area became an important transport hub. In 1881 the three railroads that reached the Straits, the Michigan Central, Grand Rapids & Indiana, and the Detroit, Mackinac & Marquette, jointly established the Mackinac Transportation Company to operate a railroad car ferry service across the straits and connect the two peninsulas.

Improved highways along the eastern shores of the Lower Peninsula brought increased automobile traffic to the Straits region starting in the 1910s. The state of Michigan initiated an automobile ferry service between Mackinaw City and St. Ignace in 1923; it eventually operated nine ferry boats that would carry as many as 9,000 vehicles per day. Traffic backups could stretch as long as 16 miles (26 km).