The Ambassador Bridge is a large suspension bridge that crosses the Detroit River, linking Detroit, Michigan, United States, with Windsor, Ontario, Canada. It opened in 1929 and is a toll bridge that handles the most trade between the United States and Canada by volume. The bridge carries more than 25% of all goods traded between the two countries by value. A 2004 study by the Border Transportation Partnership found that 150,000 jobs in the Detroit–Windsor area and $13 billion in yearly production depend on the border crossing between the two cities.

The bridge is one of the few privately owned bridges connecting the United States and Canada. It was owned by Manuel Moroun, a wealthy businessman from Grosse Pointe, until his death in July 2020. Moroun owned the bridge through the Detroit International Bridge Company in the United States and the Canadian Transit Company in Canada. In 1979, when the bridge was sold on the New York Stock Exchange, Moroun bought shares in the companies that owned the bridge and eventually took full ownership. The bridge carries 60 to 70% of the trucks that move goods in the region. Moroun also owned Ammex Detroit duty-free stores located at both the bridge and a nearby tunnel. The Moroun family opposed the construction of the Gordie Howe International Bridge between Windsor and Detroit, claiming it would take away their right to collect tolls.

History

After the American Civil War, the Detroit River became a key route for transportation. The Michigan Central and Great Western railroads, along with others, operated on both sides of the border, connecting Chicago to the Atlantic Seaboard. To cross the river, these railroads used ferries between docks on either side. However, the ferries could not handle the large amount of goods and people needing to cross. This led to long delays, with between 700 and 1,000 freight cars waiting to cross the river and many passengers stuck in transit. Grain stored in Chicago could not be sent to eastern markets, and foreign goods in eastern warehouses could not be sent west. These delays raised the cost of goods, and both merchants and farmers asked the railroads to find a solution.

The Michigan Central proposed building a tunnel under the river with help from the Great Western Railway. Construction began in 1871 but stopped the next year when air systems failed. In 1873, plans shifted to building a railroad bridge over the river. The U.S. Army Corps of Engineers studied the idea, but shipping companies on the Great Lakes opposed it, fearing the bridge would harm navigation. Discussions continued for years without success. In 1889, the U.S. Congress requested a new study, but no bridge was approved. Finally, in 1909–10, the Michigan Central built the Detroit River Tunnel to carry trains under the river. This helped the Michigan Central and Great Western railroads, but other railroads still wanted a bridge. In 1919, plans for a bridge were revived to celebrate the end of World War I and honor young people from Canada and the United States who served in the war.

Neither Ontario nor Michigan wanted to pay for a river crossing. Michigan automakers then decided to build a bridge to connect the Midwest to central Canada. After forming a bridge company, the project faced problems when a Toronto financier hired to sell the company’s shares instead stole the money and fled. He was later convicted of murder and committed suicide in prison. Bridge supporters turned to Joseph A. Bower, a New York businessman who helped save struggling companies. Bower raised $12 million for the project. Henry Ford, who supported the effort, said, "The only way things can be done today is by private business." The bridge was built with money from Detroit business leaders who formed the Detroit International Bridge Corporation.

Later, Berkshire Hathaway bought a quarter of the company’s shares but sold them to Manuel Moroun, a local trucking entrepreneur. Moroun eventually bought more shares and took full control of the company.

In April 1930, shortly after the bridge opened, a Canadian immigration inspector jumped to his death. Others later tried to jump from the bridge, and some divers considered it a place to set a record. After studying the height and water currents, they decided not to attempt it.

In November 2000, a scaffold collapsed on the bridge, sending three workers into the river and leaving four others hanging from safety harnesses. One worker, Jamie Barker, died. An engineer named George Snowden was punished for his role in the collapse. In 2012, a design Snowden approved caused a stage collapse in Toronto. Snowden’s associate, Domenic Cugliari, was also involved in both accidents.

In July 2023, a construction worker named Spencer Baker fell from scaffolding into the river but was rescued with unspecified injuries.

In February 2022, during the Freedom Convoy protests in Canada, protesters blocked the Ambassador Bridge, stopping all traffic. The bridge was closed for two days before reopening. Later, protesters returned, forcing traffic to shift to the Blue Water Bridge between Sarnia and Port Huron.

In 2025, it was reported that some undocumented immigrants accidentally drove onto the bridge and were detained by U.S. Customs and Border Protection. Michigan Immigrant Rights Center said over 200 people were detained between January and March 2025, most of whom had taken the wrong exit. The group asked for clearer signs to prevent drivers from accidentally crossing the border.

Design

The bridge over the Detroit River had the longest part that hangs in the world when it was finished in 1929—1,850 feet (560 m). This record stayed until the George Washington Bridge between New York and New Jersey opened in 1931. The bridge’s total length is 7,500 feet (2,286 m). Construction started in 1927 and was completed in 1929. The main company responsible for building the bridge was the McClintic-Marshall Company of Pittsburgh, Pennsylvania.

The bridge uses 21,000 short tons (19,000 tonnes) of steel, and the road rises as high as 152 feet (46 m) above the river. Only the main part over the river is held up by cables; the parts near the main pillars are supported by steel in a structure called a cantilever truss.

The bridge originally had a sidewalk on its southwest side. After the September 11 attacks, people walking or riding bikes were not allowed on the bridge because of security rules. Before that, the sidewalk was closed for many years because of repairs and painting. The unused sidewalk was removed in 2013 during a project to replace the road surface and widen the lanes.

The bridge was originally painted black. Between 1995 and 2000, it was repaired and repainted teal.

Granite blocks that were first used on the U.S. side were given to the Windsor Parks and Recreation Department and are now used on paths in Windsor parks.

The Ambassador Bridge is the busiest crossing between Canada and the United States. It has four lanes and carries more than 10,000 commercial trucks on a typical weekday. A major redesign of the U.S. plaza, called the Gateway Project, was completed in July 2009. It connects to Interstate 96 (I-96) and I-75 on the American side and Ontario Highway 3 on the Canadian side. The Canadian end of the bridge connects to busy city streets in west Windsor, causing traffic delays.

The privately owned bridge carries about 25% of all road traffic between Canada and the United States.

Transport Canada reported the following truck traffic percentages for the five largest U.S.–Canada border crossings in 2011:

• 24.4% for Windsor-Ambassador Bridge
• 14.4% for Sarnia–Blue Water Bridge, which connects Port Huron, Michigan, with Point Edward, Ontario
• 11.4% for Fort Erie–Peace Bridge, which connects Buffalo, New York, with Fort Erie, Ontario
• 7.0% for Peace Arch Border Crossing, Pacific Highway/Douglas, which connects the U.S. state of Washington with British Columbia
• 6.6% for Niagara Falls–Queenston Bridge, which connects Lewiston, New York, with Queenston, Ontario.

In 2024, 2.3 million trucks crossed the Ambassador Bridge, which was an 11.1% drop from the previous year. This was the lowest traffic level on record, except for 2009 during the global financial crisis and 2020 during the COVID-19 pandemic.

Additional bridge proposals

In 2009, the Canadian government tried to buy the Ambassador Bridge from Matthew Moroun for about $2 billion. However, discussions ended when Moroun asked for $3 billion and additional benefits.

In June 2012, the Canadian and U.S. governments approved plans for the Gordie Howe International Bridge, proposed by the Detroit River International Crossing (DRIC) commission. This new bridge, located farther down the river between Detroit and Windsor, will be owned and operated by the Windsor–Detroit Bridge Authority, a company controlled by the Canadian federal government.

Moroun opposed the new bridge and filed a lawsuit against the Canadian and Michigan governments to stop its construction. He also proposed building a second span of the Ambassador Bridge, which he would own. Some people believe Moroun’s opposition was because he feared losing money from selling duty-free gasoline, which avoids about 60 cents per gallon in taxes, even though the price for customers is only slightly lower. In 2011, a judge dismissed Moroun’s lawsuit, stating there was not enough reason to continue it. Moroun later said a public bridge might make the Ambassador Bridge unprofitable.

Canadian and Michigan officials continued supporting the Gordie Howe International Bridge because it connects the Canadian E.C. Row Expressway and the 2015 extension of Ontario Highway 401 (which runs alongside the Windsor–Essex Parkway) with U.S. highways I-75 and I-96 in Michigan. This design reduces traffic congestion in Windsor and avoids using local roads. A second span next to the Ambassador Bridge alone does not solve traffic issues on Huron Church Road in Windsor. While some traffic lights have been removed due to the expansion of Highway 401 (Herb Gray Parkway), which connects to the Gordie Howe Bridge, the final path to the Ambassador Bridge still uses crowded Windsor streets.

In 2007, the company that owns the Ambassador Bridge received a permit from the Michigan Department of Environmental Quality to build a new bridge near the existing one. This permit expired in 2012. In 2016, the U.S. Coast Guard approved the company to build the new span. As of 2021, construction cannot begin until Moroun resolves a problem with a 2017 permit issued by Transport Canada for the Canadian side of the bridge. The Coast Guard permit required the existing Ambassador Bridge to remain and be repaired, while the Transport Canada permit required the existing bridge to be removed.

In 2022, a five-year permit from Transport Canada expired. Transportation Minister Omar Alghabra said talks between the Canadian government, the City of Windsor, and the bridge company were still happening.

In 2025, the Windsor Star reported that the bridge company had given up on building a second span. A local Windsor council member said the company no longer plans to build the replacement span. The company also planned to build a secondary truck inspection facility closer to the bridge.

Legal issues and criticisms

The bridge's private ownership has raised concerns because it handles about 25% of trade between Canada and the United States. Even though other routes, like the nearby Detroit–Windsor Tunnel, are available, the bridge is still very important because it connects major cities. However, the tunnel does not allow certain vehicles to use it.

In 2010 and 2011, the Wayne County Circuit Court ruled that the Detroit International Bridge Company had violated court orders by not connecting bridge access roads to I-75 and I-96, as required by the Gateway Project. These improvements are usually managed by the state government, but the company delayed them during negotiations. At one time, Matty Moroun and his top assistant, Dan Stamper, were jailed for refusing to complete the on-ramps.

After many years of legal disputes, local efforts to reduce heavy truck traffic near homes, and delays caused by Matty Moroun, the Michigan Department of Transportation (MDOT) took over the I-75/I-96 on-ramp project. The ramps were completed in September 2012 after six months of construction. One reason for delays in the Gateway Project may have been Moroun’s attempt to direct traffic near his profitable duty-free store and fuel pumps, which are among only two border locations that sell untaxed fuel (the other is International Falls, Minnesota). Critics argued that money from fuel sales did not go toward fixing Michigan’s underfunded highways but instead went directly to Moroun.

Large trucks that follow the International Fuel Tax Agreement, which is meant to apply Ontario taxes and partially refund Michigan taxes on fuel bought in Detroit and used on Ontario’s Highway 401, may lose their right to the Michigan IFTA refund. This is because the tax was never paid. In 2012, the Michigan Department of Agriculture and Rural Development sued Moroun’s company, Ammex, for incorrectly labeling motor fuel as 93 octane when tests showed it was as low as 91.2 octane.

In 2015, Windsor city officials pointed out the poor condition of the bridge and the danger from broken concrete on its structure. In response, Matt Moroun claimed the city was trying to stop the company from repairing or rebuilding the bridge because the Canadian government supports plans for a new bridge across the Detroit River farther downstream.