The bridge, over the Detroit River, had the longest suspended central span in the world when it was completed in 1929 — 1,850 feet (564 m), a title it would hold until 1931. The total bridge length is 7,500 feet (2,286 m). It is the busiest international border crossing in North America in terms of trade volume: more than 25 percent of all merchandise trade between the United States and Canada crosses the bridge. Construction began in 1927 and was completed in 1929. The architect was the McClintic-Marshall Company of Pittsburgh, Pennsylvania.
The bridge is styled in a mixture of Art Deco and Streamline Moderne architectural designs, with some Gothic architecture blended in. It is made primarily out of steel; however, the two main towers on each side of the river are made of a steel-silicon alloy which rise up from concrete piers. The towers rise 386 feet (118 m) above the river, and plunge 115 feet (35 m) below the surface of the Detroit River. The bridge is made up of 21,000 tons 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 approaches to the main pillars are held up by steel in a cantilever truss structure.
The four-lane bridge carries more than 10,000 commercial vehicles on a typical weekday. When a major redesign of the U.S. plaza is completed in 2008, the bridge will provide direct access to and from Interstate 75 and Interstate 96 on the U.S. side and Highway 3 and Highway 401 on Canadian side. The Ambassador Bridge enhancement project calls for a twin span to be built across the Detroit River.
Due to the extremely high traffic volume, the American and Canadian governments are jointly examining proposals for the construction of a second bridge downriver. The line-ups for trucks can easily be 8 miles (12.9 km) in length; shortly after the September 11th attacks, trucks were backed up for over 34 kilometres (21.1 mi), to just past the Belle River Road interchange on Highway 401. In June 2008, construction on seven new toll booths began as part of the Ambassador Bridge Gateway Project. Bridge president Dan Stamper stated, "It's the equivalent of building a new tunnel. I think that's the kind of booths the tunnel has available so what we've really done is build a new border crossing in Detroit for the travelers". He also stated that many more amenities would be added to make travel easier.
Some of the concrete from the original roadbed of the Ambassador Bridge has been used in Windsor's parks and bike trails.