When was the St Lawrence Seaway completed?

Stretching 2,342 miles from Lake Superior to the Atlantic, the Saint Lawrence Seaway opens the industrial and agricultural heart of North America to deep-draft ocean vessels. One of the largest system of channels, locks and canals in the world, the Seaway allow ocean-going vessels to travel from the Atlantic Ocean to the Great Lakes, as far inland as the western end of Lake Superior. Together with the river, the waterway forms hydrographic system of east-central North America. It is of vital economic and geographic importance for the US and Canada.

The Seaway was first opened for vessels in 1959. It was preceded by a lot of other canals. The construction of the comprehensive waterway is widely considered one of the greatest engineering feats in history of all time. Seven locks were built in the Montreal-Lake Ontario section of the Seaway, five Canadian and two U.S., in order to lift vessels to 246 feet (75 meters) above sea level. First proposals for the creation of such a waterway were made in the 1890s, and the serious work began in 1954. The Seaway celebrated its 55th anniversary in 2014.