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HomeMI HistoryMI HistoryThe Story of the Mighty Mac

The Story of the Mighty Mac

Michigan has two peninsulas. The upper peninsula and the lower peninsula are separated by a body of water called the Straits of Mackinac. The Straits of Mackinac connect Lake Michigan with Lake Huron. The straits are three and a half miles wide and have a maximum depth of 210 feet at the middle of the straits.

In the 1800s when the mining and timber industries became a more important part of the Michigan economy, a need for a connection between the upper and lower peninsulas became more and more evident. In 1881 the three railroad companies that provided services to northern Michigan decided to create a company together (the Mackinac Transportation Company). The Mackinac Transportation Company was jointly founded by the Grand Rapids and Indiana railroad; The Detroit, Mackinac and Marquette Railroad; and the Michigan Central Railroad. The goal of the Mackinac Transportation Company was to create a 12-month ferry service to connect their three railheads in the two peninsulas. The company brought into service several successive ships to ferry people and train cars and for use as an icebreaker in the winter months. The company underestimated the capacity required for the ferry service to be profitable.

In 1884, the Lansing Republican dated February 5, 1884, reprinted a story from the Grand Traverse Herald “pointing out that the experiment to provide all-year service across the Straits by boat had failed, and that if a great east-west route were ever to be established through Michigan a bridge or tunnel would be required.” [2]

With the dedication of the Brooklyn Bridge in 1883, the idea of a bridge over the straits of Mackinac became a more realistic idea. In 1888 the board of directors of the Grand Hotel on Mackinac Island where Cornelius Vanderbilt said, “We now have the largest, well-equipped hotel of its kind in the world for a short season business. Now what we need is a bridge across the Straits.”[2] The idea of a bridge was still a long way from being realized due to lack of funding and technological issues of crossing 5 miles of water.

In the early 1900’s, with the widespread availability of automobiles, the desire of the public to travel to the Upper Peninsula grew. Ferry services were created to transport vehicles and people across the Straits. “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).” [3] This situation at the Straits became impractical as the population and the desire for travel between the peninsulas grew. Talks of building a bridge increased.

An estimated cost of 3.4 million dollars was determined but funding was difficult to obtain. The Mackinac Straits Bridge Authority “made two attempts between 1934 and 1936 to obtain loans and grants from the Federal Emergency Administration of Public Works, but P.W.A. refused both applications despite endorsement by the U.S. Army Corps of Engineers and the report that the late President Roosevelt favored the bridge.” [2]  In 1946 the outbreak of the Korean War stopped the bridge project, and the Mackinac Straits Bridge Authority was abolished.  

In the 1950’s, The State of Michigan reinstated the Mackinac Straits Bridge Authority which researched the feasibility of the financing and construction of a suspension bridge across the Straits yet again. This time the estimate rose to $86 million. Ultimately the money for the Mackinac bridge was procured through the sale of bonds and people all over the country purchased them. Construction of what would become the world’s longest suspension bridge at the time, at a length of 5 miles, began in May 1954.

The Mackinac Bridge, aka the Mighty Mac, was designed by the engineer Dr. David B. Steinman. “Steinman had published a theoretical analysis of suspension-bridge stability problems, which recommended that future bridge designs include deep stiffening trusses to support the bridge deck and an open-grid roadway to reduce its wind resistance. Both features were incorporated into the design of the Mackinac Bridge. The stiffening truss is open to reduce wind resistance. The road deck is shaped as an airfoil to provide lift in a cross wind, and the center two lanes are open grid to allow vertical (upward) air flow, which fairly precisely cancels the lift, making the roadway stable in design in winds of up to 150 miles per hour (240 km/h).”[3] The Mackinac Bridge was designed specifically to withstand the high winds and temperature changes experienced in northern Michigan. In severe wind conditions the deck at center span is designed to move up to 35 feet.

On November 1, 1957, the Mackinaw Bridge finally opened. The structure took 48 months to complete with over 3,500 workers and $99,800,000 dollars. The main bridge cables are made from 42,000 miles of wire and the towers stand 554 feet above the water and stretch 210 feet below down to the bedrock. During the construction of the bridge five workers perished. There is a memorial to these men located at Bridge View Park on the Upper Peninsula side of the bridge.

Some other notable statistics about the construction include:

§  71,300 tons of structural steel

§  931,000 tons of concrete

§  4,851,700 steel rivets

§  1,016,600 steel bolts

§  1,024,500 tons in total weight

Photo by Dale Cogan

The bridge is now funded through tolls, $2 per axle, that motorists pay to cross. Pedestrians and bicycles are prohibited from crossing. An exception is Labor Day when the bridge is closed to automobile traffic and pedestrians are allowed to walk from Mackinaw City to St. Ignace for the Bridge Walk.  This event has been held yearly since 1959.

The story of the Mackinac Bridge spans over 73 years from conception to completion. It is an engineering marvel and a testament to human persistence in solving problems. The bridge united the state of Michigan from two separate entities into one.

Source references.

1. Hilton, George H. (2003). The Great Lakes Car Ferries. Montevallo Historical Press. ISBN 978-0965862431

2. MDOT Mackinaw Bridge Authority

3. “Mackinac Bridge”. American Society of Civil Engineers. Retrieved January 29, 2022.

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