When was the St. Lawrence Seaway opened?

The St. Lawrence Seaway opened on June 26, 1959 with a ceremony at St-Lambert, Quebec attended by Queen Elizabeth II and US President Dwight Eisenhower. The Seaway is a joint Canada-US engineering project of canals, locks, and channels that made the Great Lakes accessible to ocean-going ships from the Atlantic Ocean for the first time. The Seaway and the related St. Lawrence power project transformed shipping, industry, and electric power in eastern Canada and the central United States.

The Seaway extends 3,769 kilometres from Montreal at the western limit of ocean shipping (via the Lachine Canal) up the St. Lawrence River to the western end of Lake Superior at Duluth, Minnesota and Thunder Bay, Ontario. The 1959 opening completed the joint Canada-US Seaway project authorised by the Canadian St. Lawrence Seaway Authority Act of December 21, 1951 and the US Wiley-Dondero Act of May 13, 1954. Construction began in August 1954 and took five years to complete. The total cost was about 470 million Canadian dollars (about 330 million US dollars), of which Canada paid about 75 per cent.

The Seaway has 15 locks: 7 in the Welland Canal (connecting Lake Ontario and Lake Erie around Niagara Falls), 7 in the Montreal-Lake Ontario section, and 1 in the Sault Ste. Marie Locks (connecting Lakes Huron and Superior, the American Soo Locks at Sault Ste. Marie, Michigan). The lift in the Welland Canal locks is about 99.5 metres total to overcome the Niagara Escarpment. Each lock can handle ships up to 222.5 metres long with 23.8 metres beam (the Seawaymax). The associated St. Lawrence Power Project (with the Moses-Saunders Power Dam between Massena, New York and Cornwall, Ontario) generates about 13.5 billion kilowatt-hours per year of hydroelectric power.

The Seaway's construction had major social consequences. About 6,500 residents were displaced from villages along the international section of the St. Lawrence. The Lost Villages of Iroquois, Aultsville, Farran's Point, Dickinson's Landing, Wales, Moulinette, Mille Roches, Maple Grove, Sheek's Island, and Woodlands were flooded under Lake St. Lawrence. Indigenous communities including the Mohawk reserve of Akwesasne lost large amounts of land. The Seaway's economic impact was transformative. Iron ore from the Quebec-Labrador trough could now be shipped efficiently to steel mills around the Great Lakes. Grain from prairie farms moved more cheaply to world markets. The Seaway today carries about 38 million tonnes of cargo annually, mostly iron ore, grain, coal, and chemicals. Climate change and reduced ice cover are extending the navigation season; the Seaway typically operates from late March to late December.