A transporter bridge, also known as a ferry bridge or aerial transfer bridge, is a type of movable bridge that carries a segment of roadway across a river. The gondola is slung from a tall span by wires or a metal frame. The design has been used to cross navigable rivers or other bodies of water, where there is a requirement for ship traffic to be able to pass. This has been a rare type of bridge, with fewer than two dozen built. There are just twelve that continue to be used today, including one converted into a lift bridge and one designed as, but not yet operating as, a transporter bridge.

The Aerial Lift Bridge, earlier known as the Aerial Bridge or Aerial Ferry Bridge, is a landmark in the port city of Duluth, Minnesota. The span began life in 1905 as the United States' first transporter bridge: Only one other was ever constructed in the country, Sky Ride in Chicago. The span was converted in 1929–1930 to a vertical-lift bridge, also rather uncommon, although there are six such bridges along Ontario's Welland Canal. It remains in operation. The bridge is owned and operated by the City of Duluth. The bridge was added to the National Register of Historic Places on May 22, 1973. The United States Army Corps of Engineers maintains a nearby maritime museum.