The Ambassador Bridge is an international suspension bridge that spans the Detroit River, connecting Detroit, Michigan, United States, with Windsor, Ontario, Canada. It opened in 1929 and is a toll bridge that serves as the busiest international border crossing in North America for trade volume. The bridge carries more than 25% of all merchandise trade between the United States and Canada by value. A 2004 study by the Border Transportation Partnership found that 150,000 jobs in the Detroit–Windsor region and $13 billion in annual production depend on the Detroit–Windsor international border crossing.

The bridge is one of the few privately owned crossings between the United States and Canada. It was owned by Manuel Moroun, a billionaire 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, Moroun purchased shares in the bridge after it was sold on the New York Stock Exchange. He eventually acquired full ownership. The bridge handles 60 to 70% of commercial truck traffic in the region. Moroun also owned the Ammex Detroit duty-free stores located at both the bridge and the tunnel. The Moroun family opposed the construction of the Gordie Howe International Bridge between Windsor and Detroit, claiming it would interfere with their right to collect tolls.

History

The route across the Detroit River became important for moving people and goods after the American Civil War. Railroads like the Michigan Central and Great Western 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 number of freight cars and passengers, causing delays. In Chicago, warehouses had to store grain that could not be sent east, and goods in the east had to wait to be sent west. These delays increased the cost of goods, and both merchants and farmers wanted the railroads to fix the problem.

The Michigan Central Railroad proposed building a tunnel under the river with help from the Great Western Railway. Construction began in 1871 but stopped in 1872 when the air system failed. Plans then 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 boat traffic. No agreement was reached, and no bridge was approved. In 1889, Congress asked for another study, but no bridge was built. 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.

Plans for a bridge were revived in 1919 to celebrate the end of World War I and honor young people from Canada and the United States who served in the war. However, neither Ontario nor Michigan wanted to pay for the bridge. Michigan automakers decided to build the bridge themselves. They created a bridge company, but the project faced problems when a Toronto financier stole money and later committed suicide in prison after being convicted of murder. The bridge boosters turned to Joseph A. Bower, a businessman who helped fix failing companies. Bower raised $12 million, and Henry Ford supported the project. The bridge was built by Detroit business people through 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 made the bridge a private 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, but they were discouraged after studying the height and water current.

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

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

During the Freedom Convoy protests in 2022, protesters blocked the Ambassador Bridge in Canada. Traffic stopped completely on February 7, 2022, and resumed the next day. The blockade continued, and some drivers were redirected 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. The 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 mistakes.

Design

The bridge over the Detroit River had the longest main span in the world when it was completed in 1929—1,850 feet (560 m). This record remained 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 began in 1927 and was completed in 1929. The general contractor and steel erector was the McClintic-Marshall Company of Pittsburgh, Pennsylvania.

The bridge is made of 21,000 tons (19,000 tonnes) of steel, and the roadway rises as high as 152 feet (46 m) above the Detroit River. Only the main span over the river is supported by suspension cables; the sections near the main pillars are held up by steel in a cantilever truss structure.

The bridge originally had a sidewalk on its southwest side. After the September 11 attacks, pedestrians and bicycles were not allowed to cross the bridge because of increased security measures. For years before September 11, 2001, the sidewalk was closed due to ongoing maintenance and repainting. The unused sidewalk was removed in 2013 as part of a project to replace the bridge deck and widen the lanes.

Originally painted gloss black, the bridge was repainted teal between 1995 and 2000 during a five-year refurbishment.

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

The Ambassador Bridge is the busiest crossing on the Canada–United States border. The four-lane bridge carries more than 10,000 commercial vehicles on a typical weekday. The Gateway Project, a major redesign of the U.S. plaza completed in July 2009, provides direct access 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, leading to traffic congestion.

The privately owned bridge carries about 25% of roadway trade between Canada and the United States.

Transport Canada reported the following distribution for the five largest U.S.–Canada border crossings by trucks in 2011:

• 24.4% for Windsor-Ambassador Bridge
• 14.4% for Sarnia–Blue Water Bridge, which links 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 links the U.S. State of Washington with British Columbia by land
• 6.6% for Niagara Falls–Queenston Bridge, which links Lewiston, New York, with Queenston, Ontario.

In 2024, 2.3 million trucks passed over the Ambassador Bridge, a decrease of 11.1% 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 the summer of 2009, the Canadian government said it wanted to buy the Ambassador Bridge from 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 government-owned company in Canada.

Moroun opposed this plan. He filed a lawsuit against the governments of Canada and Michigan to stop the bridge’s construction. He also proposed building a second section of the Ambassador Bridge, which he would own. Critics say Moroun’s opposition may have been because he feared losing money from selling duty-free gasoline, which avoids about 60 cents per gallon in taxes, even though prices for consumers are only slightly lower. In May 2011, a judge said the case had no valid reason to continue. In September 2011, Moroun stated that a public bridge might make the Ambassador Bridge unprofitable.

Canadian and Michigan officials continued to support 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 bridge would avoid traffic in Windsor’s city streets and reduce congestion. A second section of the Ambassador Bridge alone would not solve traffic problems on Huron Church Road in Windsor. Although some traffic lights in Windsor have been removed due to the expansion of Highway 401 (Herb Gray Parkway), which connects to the Gordie Howe Bridge, the final route to the Ambassador Bridge still uses crowded city streets.

In 2007, the company that owns the Ambassador Bridge received a permit from Michigan’s environmental department to build a new bridge next to the existing one. This permit expired in 2012. In 2016, the U.S. Coast Guard gave the company permission to build the new section. However, as of 2021, construction could not begin until Moroun resolved a conflict with a permit issued by Canada’s Transport Canada in 2017. The Coast Guard permit required the existing Ambassador Bridge to remain and be fixed, while the Canadian permit required the existing bridge to be removed.

In 2022, a five-year permit from Transport Canada expired. Canada’s transportation minister said discussions between the government, the city of Windsor, and the bridge company were still happening.

In 2025, the Windsor Star newspaper reported that the bridge company had stopped planning a second section of the Ambassador Bridge. A local Windsor official said the company no longer intended to build the replacement span. The company also planned to construct 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. While other routes, such as the nearby Detroit–Windsor Tunnel, exist to avoid a monopoly, the bridge is important because it connects major cities. 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 was not following court orders. The company failed to connect 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, community efforts to reduce heavy truck traffic in neighborhoods, and delays caused by Matty Moroun, the Michigan Department of Transportation (MDOT) took control of the I-75/I-96 on-ramp project. The ramps were completed and opened 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 the few border locations selling untaxed fuel. Critics argued that money from fuel sales was not used to repair Michigan’s underfunded roads but instead went directly to Moroun.

Truck operators under the International Fuel Tax Agreement, which is meant to apply Ontario taxes and partially refund Michigan taxes for 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 falsely 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 damaged concrete in its structure. In response, Matt Moroun claimed the city was trying to block the company’s plans to repair or rebuild the bridge because the Canadian government supports building a new bridge across the Detroit River farther downstream.