Mackinac Bridge 1957

Mackinac Bridge 1957

© Rudolph Arnstein

© Josephine Godby

Mackinac Bridge

The 'Mighty Mac' crosses the 8km (5 mile) straits.

Key Facts

Four-lane road bridge

Part of Interstate 75

Also known as Mighty Mac or Big Mac


Michigan, USA

Across the Straits of Mackinac

Between Mackinac City and St Ignace

Designers / Engineers

David B. Steinman

Robinson & Steinman


Central suspension bridge

1,158m main span

8,038m total length

Main contractors

American Bridge Company

Merritt-Chapman & Scott


Began 7 May 1954

Opened 1 November 1957

The Bridge

In the early 1950s there was significant growth in the use of motor vehicles in the USA and the national highway system was expanding. There were increasingly delays crossing the Straits of Mackinac, in Michigan, via the ferry service and a bridge was proposed. The renowned American civil engineer, David B Steinman, was appointed to design the bridge and construction started in 1954.

The bridge is a total length of 8,038m, with a central span of 1,158m, and connects Lower and Upper Michigan. Steinman used a deep stiffening truss to support the road deck to ensure aerodynamic stability on the suspended section. He was acutely aware of the collapse of the Tacoma Narrows Bridge in 1940 and had indeed warned that bridge’s designers of his concerns. He reportedly designed the Mackinac Bridge to withstand winds of over 300mph.

The piers and towers were constructed in the summer of 1954 and 1955 due to the lakes freezing and no construction was possible in the winter. It was opened to traffic in 1957 and has become an icon of Michigan and is regarded as Steinman’s greatest achievement.

© Aaron Burden

Other long-span bridges