The Saint-Lawrence Seaway is a system of locks, canals, and channels that allows ships to travel from the Atlantic Ocean to the Great Lakes in North America. It connects the Saint Lawrence River to the Great Lakes, facilitating international trade and transportation. The seaway was officially opened in 1959 and is a vital route for cargo ships carrying goods like grain, iron ore, and coal. The seaway spans approximately 2,300 miles and includes several key locks, such as the Welland Canal and the Montreal-Lake Ontario Navigation System. It plays a crucial role in the economies of both Canada and the United States, supporting industries and providing access to inland markets.