The Mackinac Bridge (pronounced MAK-uh-naw; also called 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, an area of water that connects Lake Michigan and Lake Huron, two of the Great Lakes. Opened in 1957, the bridge is 26,372 feet long (about 4.995 miles or 8.038 kilometers). It is the world's 29th-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 carries the Lake Michigan and Huron parts of the Great Lakes Circle Tour across the straits. It is also a part 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.

The idea for the bridge began in the 1880s. It was designed by engineer David B. Steinman and completed in 1957 after many years of effort to start construction. The bridge is now an important symbol of the state of Michigan.

Length

The bridge opened on November 1, 1957, connecting two peninsulas that had been linked by ferries for many years. At that time, it was officially named the "world's longest suspension bridge between anchorages," which allowed a comparison to the Golden Gate Bridge, which has a longer center span between its towers, and the San Francisco–Oakland Bay Bridge, which has an anchorage in the middle.

Today, it is still the longest suspension bridge with two towers between anchorages in the Western Hemisphere. Longer distances between anchorages have been built in the Eastern Hemisphere, such as the Akashi Kaikyō Bridge in Japan (6,532 feet or 1,991 meters). However, the long sections of the Mackinac Bridge that extend toward the anchorages make its total shoreline-to-shoreline length of 26,372 feet (8,038 meters)—28 feet (8.5 meters) short of five miles (8.0 kilometers)—longer than the Akashi Kaikyō Bridge (2.4 miles or 3.9 kilometers).

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

History

Before Europeans arrived in the 1600s, the Algonquian people living near the straits called the area Michilimackinac, which means "Place of the Great Turtle." This name is believed to describe the shape of Mackinac Island. Scholars continue to debate the meaning of the word. Trading posts near the Straits of Mackinac had the most people during the summer, when trading was busiest. These posts also became places where different tribes met.

As the use of Michigan’s minerals and wood grew in the 1800s, the area became an important transportation center. In 1881, three railroads that reached the Straits—Michigan Central, Grand Rapids & Indiana, and Detroit, Mackinac & Marquette—formed the Mackinac Transportation Company. This group started a ferry service to carry railroad cars across the straits and connect the two parts of the state.

Improved roads along the eastern side of the Lower Peninsula brought more car traffic to the Straits area starting in the 1910s. In 1923, the state of Michigan began a ferry service between Mackinaw City and St. Ignace. This service used nine boats and carried up to 9,000 cars each day. Traffic delays sometimes stretched for 16 miles (26 km).

After the Brooklyn Bridge opened in 1883, people began to imagine a similar bridge across the Straits of Mackinac. In 1884, a store owner in St. Ignace published a newspaper ad showing an artist’s drawing of the Brooklyn Bridge with the caption "Proposed bridge across the Straits of Mackinac."

The idea of building a bridge was discussed in the Michigan Legislature as early as the 1880s. At that time, the area was becoming a popular tourist spot, especially after Mackinac National Park was created on Mackinac Island in 1875.

In 1888, Cornelius Vanderbilt II, a businessman, suggested building a bridge across the straits, similar to one being built in Scotland. He believed the bridge would help trade and extend the tourist season for hotels like the Grand Hotel on Mackinac Island.

For many years, no action was taken. In 1920, the state highway commissioner proposed a floating tunnel across the straits. In 1923, the state legislature ordered the creation of a ferry service. As more people used ferries, the push to build a bridge grew.

By 1928, ferry service had become so popular and expensive to operate that Governor Fred W. Green ordered a study on building a bridge. The study found the idea was possible, estimating the cost at $30 million (about $432 million in 2024).

In 1934, the Michigan Legislature created the Mackinac Straits Bridge Authority to explore ways to build and fund the bridge. The group tried to get federal money during the Great Depression but failed. The U.S. Army Corps of Engineers and President Franklin D. Roosevelt supported the project, but Congress did not provide funds. Between 1936 and 1940, the Authority studied possible routes and conducted geological surveys.

Early plans for the bridge included a three-lane road, a railroad track under the bridge, and a design similar to the San Francisco–Oakland Bay Bridge. However, building an anchorage in the deepest part of the straits might have been difficult. A 4,000-foot (1,219 m) concrete causeway was built in shallow water from 1939 to 1941. Engineers faced challenges because ice from winter lake freezes could damage the bridge.

Work on the bridge was paused during World War II. The Mackinac Straits Bridge Authority was dissolved in 1947, but a new Mackinac Bridge Authority was created in 1950. Engineers were hired for the project in 1950. By then, cars waiting for the ferry could take up to five hours to cross, and the ferry’s capacity of 460 cars per hour could not meet the demand for a bridge.

In 1952, the state legislature approved $85 million (about $804 million in 2024) in bonds for the bridge. A weak bond market delayed the project for over a year. David B. Steinman became the design engineer in 1953, and by the end of that year, contracts were finalized. The total cost was estimated at $95 million (about $887 million in 2024), with completion expected by November 1, 1956. Tolls collected over 20 years would pay for the bridge. Construction began on May 7, 1954.

The Merritt-Chapman and Scott Corporation of New York was hired to build the bridge’s foundation for $25.7 million (about $240 million in 2024). The American Bridge Division of United States Steel Corporation was hired to build the steel structure for over $44 million (about $407 million in 2024). Construction took three and a half years, using the causeway built earlier. The bridge cost $100 million total, and five workers lost their lives during the project. None of them were buried in the bridge. It opened on November 1, 1957, and ferry service ended the same day. The bridge was officially dedicated on June 25, 1958.

Governor G. Mennen Williams was in office during the bridge’s construction. He was the first to pay the toll (then $3.25, about $37.26 in 2025) and took the last ferry ride. He later started the tradition of governors walking across the bridge every Labor Day. Senator Prentiss M. Brown, known as the "father of the Mackinac Bridge," was honored with a special token by the Mackinac Bridge Authority.

The bridge reached its 100 millionth crossing on June 25, 1998, exactly 40 years after its dedication. The 50th anniversary of the bridge’s opening was celebrated on November 1, 2007, at a viewing park near St. Ignace. In 2010, the American Society of Civil Engineers named the bridge a National Historic Civil Engineering Landmark.

Facts and figures

The Mackinac Bridge is a toll bridge on Interstate 75 (I-75). At first, US Highway 27 (US 27) was used across the bridge. In November 1960, parts of I-75 opened from Indian River to the southern end of the bridge near Mackinaw City, and US 27 was no longer used on the bridge. It is one of only three sections of I-75 that charge tolls. The other two are the American part of the International Bridge near Sault Ste. Marie, Michigan, and Alligator Alley in Florida. The current toll is $4.00 for cars and $5.00 per axle for trucks. In 2007, the Mackinac Bridge Authority raised the toll to fund a $300 million project to replace the bridge’s deck.

Painting the bridge takes seven years. Once the painting is complete, the process starts again. The current painting project began in 1999 and was expected to take 20 years because lead-based paint must be removed, which requires special disposal methods.

The bridge celebrated its 150 millionth vehicle crossing on September 6, 2009.

• Length from cable bent pier to cable bent pier: 7,400 feet (2,256 m).
• Total width of the roadway: 54 feet (16.5 m). Two outside lanes: 12 feet (3.7 m) wide each. Two inside lanes: 11 feet (3.4 m) wide each. Center mall: 2 feet (0.61 m). Catwalk, curb, and rail width: 3 feet (0.91 m) on each side.
• Width of stiffening truss in the suspended span: 68 feet (20.7 m).
• Depth of stiffening truss: 38.1 feet (11.6 m).
• Height of the roadway at mid-span: approximately 200 feet (61 m) above water level.
• Vertical clearance at normal temperature: 155 feet (47 m) at the center of the main suspension span. 135 feet (41 m) at the boundaries of the 3,000-foot-wide (914 m) navigation channel.
• Construction cost: $99.8 million (equivalent to $850 million in 2024).
• Height of towers above water: 552 feet (168 m).
• Max. depth of towers below water: 210 feet (64 m).
• Depth of water beneath the center of the bridge: 250 feet (76 m).
• Main cables: Number of wires in each cable: 12,580. Diameter of each wire: 0.196 inches (0.498 cm). Diameter of each cable: 24.5 inches (62.23 cm). Total length of wire in main cables: 42,000 miles (68,000 km).
• Total vehicle crossings, 2005: 4,236,491 (average 11,608 per day).
• Speed limit: 45 miles per hour (72 km/h) for passenger cars, 20 miles per hour (32 km/h) for heavy trucks. Heavy trucks must keep a 500-foot (150 m) space ahead.

Five workers died during the bridge’s construction:

• Diver Frank Pepper died from the bends after ascending too quickly from a depth of 140 feet (43 m) on September 16, 1954. He was taken to a decompression chamber but did not survive.
• James LeSarge, 26, fell into a caisson on October 10, 1954, and likely died from head injuries after falling 40 feet (12 m).
• Albert Abbott, 40, fell four feet (1.2 m) into the water on October 25, 1954, while working on a narrow beam. Witnesses think he had a heart attack.
• Jack Baker and Robert Koppen, both 28, died when a catwalk collapsed near the north tower on June 6, 1956. Koppen’s body was never found. Another worker suffered a broken ankle.

All five men are remembered on a plaque near the bridge’s northern end (Bridge View Park). No bodies are buried in the concrete, as some stories suggest.

One worker died after the bridge opened. Daniel Doyle fell 60 to 70 feet (18 to 21 m) from scaffolding on August 7, 1997. He survived the fall but died from the cold water temperature. His body was found the next day in 95 feet (29 m) of water.

Two

Bridge Walk

The first Mackinac Bridge Walk took place in 1958 and was led by Governor G. Mennen Williams. This event occurred during the Bridge's Dedication Ceremony in late June and has taken place on Labor Day since 1959. Until 2018, school buses from nearby districts helped transport walkers from Mackinaw City to St. Ignace to begin the walk. Thousands of people, usually led by the governor of Michigan, walk across the five-mile (8 km) bridge from St. Ignace to Mackinaw City. Before 1964, walkers traveled from Mackinaw City to St. Ignace. Until 2017, two lanes of the bridge remained open for vehicles during the event. In 2017, the policy changed to close the entire bridge to vehicle traffic for the duration of the walk. The Bridge Walk is the only day of the year when hikers can walk this section of the North Country National Scenic Trail.

Tourism

During the summer, the Upper Peninsula and Mackinac Bridge are popular places for visitors. People who visit Mackinac Island also travel to see the bridge, which interests many different kinds of visitors, such as those who enjoy bridges, bird watching, and photography. The Straits area is a favorite spot for sailing, where boats of all kinds can be used to see the bridge's structure more clearly.

In media

On June 25, 1958, the United States Postal Service (USPS) released a 3¢ stamp to celebrate the Mackinac Bridge, which had opened in November 1957. The stamp was titled "Connecting the Peninsulas of Michigan," and 107,195,200 copies were printed. In 2010, the USPS honored the bridge again with a $4.90 stamp for priority mail. This stamp was sold on February 3, 2010, and showed a "seagull's-eye view" of the bridge with a ship below. Artist Dan Cosgrove created the design using panoramic photographs. This stamp is one of several designs Cosgrove has made for the USPS.

On April 24, 1959, Captain John S. Lappo, a Strategic Air Command officer at Lockbourne AFB, flew his Boeing B-47 Stratojet beneath the Mackinac Bridge. After a general court-martial, he was permanently removed from flying duty.

In 1997, filmmaker Mark Howell produced a documentary called Building the Mighty Mac for PBS. The film included interviews with people who built the bridge and restored color footage of its construction.

A 2003 episode of the History Channel’s Modern Marvels focused on the history and construction of the Mackinac Bridge.

On July 19, 2007, the Detroit Science Center displayed an 80-foot-long (24 m), 19-foot-tall (5.8 m) scale model of the Mackinac Bridge. The exhibit was part of the bridge’s 50th anniversary celebration. Sherwin-Williams provided paint that matched the bridge’s original colors for the model.

In August 2007, the Discovery Channel’s Dirty Jobs featured the Mackinac Bridge and its maintenance crew. Host Mike Rowe and the production team filmed the episode in May 2007.

In 2007, the Michigan Department of Transportation (MDOT) included the Mackinac Bridge on the cover of the state highway map to mark its 50th anniversary.