St. Lawrence Seaway opened - Jun 26, 1959 - HISTORY.com

In a ceremony presided over by U.S. President Dwight D. Eisenhower and Queen Elizabeth II, the St. Lawrence Seaway is officially opened, creating a navigational channel from the Atlantic Ocean to all the Great Lakes. The seaway, made up of a system of canals, locks, and dredged waterways, extends a distance of nearly 2,500 miles, from the Atlantic Ocean through the Gulf of St. Lawrence to Duluth, Minnesota, on Lake Superior.

Work on the massive project was initiated by a joint U.S.-Canadian commission in 1954, and five years later, in April 1959, the icebreaker D’Iberville began the first transit of the St. Lawrence Seaway. Since its official opening, more than two billion tons of cargo, with an estimated worth of more than $300 billion, have moved along its canals and channels.