Ambassador Bridge

The Ambassador Bridge is an international suspension bridge spanning the Detroit River that connects Detroit, Michigan, United States, with Windsor, Ontario, Canada. Opened in 1929, the toll bridge has long been the busiest international border crossing in North America in terms of trade volume, historically carrying more than 25% of all merchandise trade between the United States and Canada by value — a share that may shift as the newly constructed Gordie Howe International Bridge begins drawing commercial traffic. One of the most recognizable structures on Detroit's skyline, the bridge stands as a landmark of engineering ambition, cross-border commerce, and the complex politics of privately owned infrastructure. A 2004 Border Transportation Partnership study showed that 150,000 jobs in the Detroit–Windsor region and US$13 billion in annual production depend on the Detroit–Windsor international border crossing. The bridge remains among the most economically consequential pieces of infrastructure in the Western Hemisphere.

Background and the Need for a Crossing

Detroit was a major metropolitan center by the early 20th century, but travelers and goods could only cross the border via boat. The passage across the Detroit River had been an important traffic route following the American Civil War. The Michigan Central and the Great Western railroads, in addition to others, operated on either side of the border connecting Chicago with the Atlantic Seaboard. To cross the Detroit River, these railroads operated ferries between docks on either side. The ferries lacked the capacity to handle the shipping needs of the railroads, and there were often 700–1,000 freight cars waiting to cross the river, with numerous passengers delayed in transit.

A train tunnel built between the United States and Canada under the Detroit River made transport between the two countries easier but did not completely alleviate problems. Several bridge proposals failed due to claims that it would be a navigation hazard, be too expensive, or that there would be restrictions on its use.

In the mid-1920s, John W. Austin approached Detroit financier Joseph A. Bower with a viable bridge proposal. Bower secured the necessary funding of $23.5 million, yet the plan was temporarily thwarted by Detroit Mayor John Smith, who opposed a privately owned bridge. Detroiters voted overwhelmingly in favor of the bridge construction in a referendum on June 28, 1927.

During its construction phase, the bridge was referred to simply as the Detroit River Bridge. Bower felt that the name was too impersonal but did not want the bridge named after him, so he named it the Ambassador Bridge. The bridge was celebrated as a symbol of the peaceful relationship between the United States and Canada.

Design and Construction

The McClintic-Marshall Company of Pittsburgh, Pennsylvania — the same firm that would later build the Golden Gate Bridge — was chosen for the project. Construction began in May 1927 and was completed in 1929, months ahead of schedule. The chief engineer of design was Ralph Modjeski of the firm Modjeski and Masters, whose work shaped the bridge's distinctive structural character.

Composed of Art Deco and Gothic styling, the bridge's total length is 7,490 feet. The structure is built mainly of steel — some 21,000 tons — and has a roadway that rises as high as 152 feet above the Detroit River. The twin silicon steel towers rose 386 feet above the ground and were built on concrete piers resting on bedrock 115 feet below the surface. The U.S. and Canadian terminals stand 1¾ miles apart. The roadway was 47 feet wide with an eight-foot-wide sidewalk on the west side.

Construction was not without drama. The original plans called for the then-innovative heat-treated wire cables to be used in the main suspension cables. In early 1929, the project was thrown into uncertainty when word reached Detroit that a number of broken wires had been found in the cables of the nearly completed Mount Hope Bridge in Rhode Island — a bridge that shared with the Ambassador Bridge the distinction of being the first to use heat-treated wire instead of cold-drawn steel. Three broken strands had been found near the Bristol, Rhode Island anchorage of the Mount Hope Bridge as early as January 1929. McClintic-Marshall halted work on the Ambassador Bridge and summoned a team of consultants from the Massachusetts Institute of Technology to examine the situation. Based on their report, McClintic-Marshall — with the full agreement of Joseph Bower — decided to absorb the half-million-dollar expense of removing the cables over the Detroit River and replacing them with time-tested cold-drawn steel wire. Despite this setback, the old cables were replaced with new in time to hang the roadway and open the bridge on November 11 — nine months ahead of the original schedule.

At the time of its construction, the Ambassador Bridge was the largest suspension bridge in the world, only to be surpassed two years later by the George Washington Bridge, spanning the Hudson River. Michigan has had the distinction of having twice built the longest suspension bridge in the world — the Ambassador Bridge was the first, and the Mackinac Bridge was the second.

The opening of what was then the world's longest suspension bridge had been preceded, just 21 days before, by the beginning of the crash of the New York Stock Exchange and the onset of the Great Depression. Despite this inauspicious timing, the bridge quickly became integral to regional commerce.

Ownership History

The Ambassador Bridge has been privately owned since its opening — a distinction that has defined much of its history and generated ongoing controversy.

Joseph A. Bower, a New York financier originally from Detroit, made the construction of the bridge possible. The total cost of the project was $23.5 million. The Bower family maintained control of the Ambassador Bridge until 1979, when the Central Cartage Company of Detroit, owned by Detroit-native Manuel "Matty" Moroun, purchased it.

Manuel "Matty" Moroun (June 5, 1927 – July 12, 2020) was an American billionaire businessman, most notable as the owner of the Ambassador Bridge international crossing. The bridge, which Moroun purchased from the Bower family in 1979, is one of the few privately owned international border crossings between the United States and Canada. The bridge was held by Moroun through the Detroit International Bridge Company in the United States and the Canadian Transit Company in Canada. Moroun's acquisition of the bridge had wide-ranging consequences for the Southwest Detroit neighborhood adjacent to the bridge's U.S. terminus and for the broader politics of cross-border infrastructure in the region.

To reach the bridge, freight trucks must first pass through a residential neighborhood in southwest Detroit known as Mexicantown. For many years, they drove directly through it. In 2004, Moroun signed a $258 million agreement with the city for an initiative called The Gateway Project. Under that arrangement, the government agreed to build additional roads to ease traffic, and in exchange, Moroun promised to construct entryways connecting the bridge to the highway system so that trucks would no longer need to pass through the Mexicantown neighborhood.

Following Moroun's death in July 2020, control of the bridge passed to his family. The Moroun family's continued ownership and political influence have drawn scrutiny in the years since. In 2025, the owner of the Ambassador Bridge made a $1 million donation to a political action committee supporting former President Donald Trump, a contribution that drew renewed attention to the intersection of private bridge ownership and federal border policy. U.S. Representatives Chuy Garcia and Rashida Tlaib subsequently called on federal officials to provide details about a reported meeting between the bridge's owner and Commerce Secretary Howard Lutnick, pressing for transparency about any arrangements that might affect the public interest in cross-border infrastructure.

Economic Significance

The Ambassador Bridge occupies a singular position in the trade relationship between the United States and Canada. The bridge carries 60 to 70 percent of commercial truck traffic in the region, and estimates suggest that over 10,000 vehicles cross it on weekdays. The Detroit crossings have particular significance for maintaining the supply chains of the automotive industries of both countries. Automotive trade between the United States and Canada increased from US$32 billion in 1995 to US$51 billion in 2023. The crossings also play a part in the daily lives of approximately 5,000 Canadian commuters who work in neighboring Detroit.

CNN once described the bridge as "the most economically important one-and-a-half miles of roadway in the Western Hemisphere." Custom duties from Canadian tolls on the bridge have averaged over $15,000,000 a year. In 1981, the bridge became even more prominent on Detroit's skyline with a permanent installation of lights. The illuminated towers are now visible from the Detroit Riverwalk and from the Renaissance Center plaza.

Toll rates at the Ambassador Bridge are subject to periodic adjustment. In 2026, the bridge's operator announced an increase in tolls for commercial and passenger crossings, continuing a pattern of incremental rate changes that have drawn attention from trucking industry groups and cross-border commuters alike.

Border Operations and Security

The Ambassador Bridge serves as a federally designated port of entry, with U.S. Customs and Border Protection (CBP) officers stationed at the U.S. plaza and Canadian Border Services Agency (CBSA) officers on the Canadian side. The volume of commercial traffic crossing the bridge daily makes it one of the most active CBP inspection points in the country. Officers regularly intercept contraband at the crossing; CBP Detroit officers have conducted seizures of marijuana products and other controlled substances from vehicles attempting to cross through the bridge plaza.

The bridge's layout has also generated practical concerns for ordinary motorists. The highway approach to the Ambassador Bridge on the Detroit side has a reputation among local drivers for being confusingly designed, with merge points and signage that can cause drivers unfamiliar with the area to inadvertently enter the crossing and find themselves committed to a crossing into Canada. Drivers who cross unintentionally must present themselves to Canadian border authorities before being permitted to return, a process that can take considerable time. The issue reflects a broader challenge of integrating a major international crossing into an urban street grid without a fully grade-separated approach on the American side — a shortcoming that the Gordie Howe International Bridge is designed to address through direct highway connections on both sides of the river.

Under federal law, the bridge must be inspected every two years to maintain safety standards. The Ambassador Bridge appears to have been well maintained overall, and the bridge's operator is required to file inspection reports with the U.S. Coast Guard, which has jurisdiction over navigable waterway crossings. Despite periodic reports citing the need for maintenance work on certain structural elements, no major safety failures have occurred.

The 2022 Freedom Convoy Blockade

In February 2022, the Ambassador Bridge became the focal point of one of the most significant disruptions to cross-border trade in its history. Protesters associated with the "Freedom Convoy" — a movement that originated in opposition to Canadian federal vaccine mandates — blockaded the bridge for approximately six days, halting commercial truck traffic entirely. The blockade caused an estimated several hundred million dollars in economic disruption, forcing automotive manufacturers on both sides of the border to halt or reduce production due to supply chain interruptions. The Canadian government ultimately invoked the Emergencies Act for the first time in the country's history, and Ontario courts issued injunctions requiring protesters to clear the bridge. Police cleared the blockade on February 13, 2022, restoring traffic after a halt that underscored how dependent binational manufacturing supply chains are on the uninterrupted operation of a single crossing.

The Gordie Howe International Bridge and Competition Controversy

The privately held status of the Ambassador Bridge became the subject of intense political and legal dispute when both the U.S. and Canadian governments moved to authorize a publicly owned competing crossing.

First proposed in the early 2000s, the project was met with prominent opposition by Ambassador Bridge owner Manuel "Matty" Moroun, who argued that competition from a publicly owned bridge would reduce his revenue. In June 2012, the Canadian and United States governments approved the construction of the Gordie Howe International Bridge proposed by the Detroit River International Crossing (DRIC) commission. The new bridge, located further downriver between Detroit and Windsor, would be owned and operated by the Windsor–Detroit Bridge Authority, a Crown corporation owned by the Canadian federal government.

Moroun spoke out vigorously against the proposal. He sued the governments of Canada and Michigan in an effort to stop its construction, and released a proposal to build a second span of the Ambassador Bridge — which he would own — as an alternative. Lawsuits filed by Moroun alleged that the crossing agreement was illegal and that the Ambassador Bridge held exclusivity rights. Those lawsuits were denied, along with various attempts to stop property expropriations, allowing the Gordie Howe project to continue. In summer 2009, the federal government of Canada reportedly offered to buy the Ambassador Bridge from Moroun for around $2 billion, but talks broke down when Moroun asked for $3 billion plus incentives.

The "Bridging North America" consortium was selected in July 2018 to design, build, operate, and maintain the Gordie Howe International Bridge, and construction began that month. The new bridge is designed to provide a direct connection to interstate highways on the American side and to Ontario's 400-series highway network on the Canadian side, bypassing urban surface streets entirely. A U.S. Department of Homeland Security analysis projected that the Gordie Howe Bridge would cut substantially into commercial truck traffic at the Ambassador Bridge once fully operational, a finding that significantly raised the economic stakes of the Moroun family's efforts to influence federal border policy.

The Ambassador Bridge has been criticized for its monopoly status — as large trucks are not permitted to use the Detroit–Windsor Tunnel — its private ownership, and its maintenance record. Both the bridge and the road tunnel lack direct highway connections on the Canadian side, with city streets and traffic lights between them and Ontario Highway 401. These access limitations have long been cited by transportation planners as a structural inefficiency that