The Saint Lawrence Seaway is a joint United States-Canada 370-mile seaway that permits ocean freighters to transit from the western end of Lake Superior to the Atlantic Ocean by way of a continuous chain of channels, canals, and locks. Others describe the Seaway from Montreal, Quebec, through the Welland Canal to Lake Erie.
A system of locks, canals and channels in Canada and the United States permits ocean-going vessels to travel from the Atlantic Ocean to the Great Lakes as far inland as the western end of Lake Superior. The Seaway is named for the Saint Lawrence River, which flows from Lake Ontario to the Atlantic Ocean. Legally, the Seaway extends from Montreal, Quebec, to Lake Erie and includes the Welland Canal.
This Montreal-to-Lake Erie section upstream of the Seaway is not a continuous canal; rather, it consists of several stretches of navigable channels within the river, a number of locks, and canals along the banks of the St. Lawrence River to bypass several falls, Rapids, locks, and dams along the way. A number of the locks are managed by the Saint Lawrence Seaway Management Corporation in Canada; others in the United States by the Saint Lawrence Seaway Development Corporation. The two bodies together advertise the Seaway as part of “Highway H2O”. The section of the river downstream of Montreal, which is fully within Canadian jurisdiction, is regulated by the offices of Transport Canada at the Port of Quebec.