When the Mackinac Bridge was completed, it was the world's longest suspension bridge when measured between its anchoring points.  The Golden Gate Bridge had a longer central span between towers but the Mackinac had a longer total length.  It is still the longest twin-towered suspension bridge between anchors in the western hemisphere. Its total length is 3,038 metres and its width 20.9 metres accommodating the 4 lanes of traffic on Interstate 75.   The height of the roadway at mid-span is approximately 200 feet above water level.  The towers rise up to 168.25 metres above the water.

Known affectionately as the "Mighty Mac" or the "Big Mac", it spans the Strait of Mackinac, the narrow point at which Lakes Huron and Michigan join.  It links the communities of St. Ignace and Mackinaw City.  The desire to span the gap, that had previously required a ferry connection, was mooted as early as 1880 but it took a long time to make it a reality. 



As the Mackinac Bridge Authority website explains, "... All suspension bridges are designed to move to accommodate wind, change in temperature, and weight. It is possible that the deck at center span could move as much as 35 feet (east or west) due to high winds. This would only happen under severe wind conditions. The deck would not swing or "sway" but rather move slowly in one direction based on the force and direction of the wind. After the wind subsides, the weight of the vehicles crossing would slowly move it back into center position."  They add that, " During the construction of the Mackinac Bridge in the 1950's, five men unfortunately lost their lives.  One man died in a diving accident; one man fell in a caisson while welding; one man fell into the water and drowned; and two men fell from a temporary catwalk near the top of north tower."