SAINT LAWRENCE SEAWAY

American-Canadian navigational project that provides a waterway and lock system along the upper St. Lawrence River in order to connect the Atlantic Ocean with the Great Lakes. Construction of the seaway began in 1954, and it was opened in 1959. The St. Lawrence Seaway is considered a great engineering feat. Its construction mainly involved clearing a throughway in a 186-mile (299-kilometre) stretch of the St. Lawrence River between Montreal and Lake Ontario. This project forged the final link in a complex of lakes, rivers, deepened channels, locks, and canals stretching across 2,340 miles (3,766 km) and ultimately linking Duluth, Minn., with the head of the Gulf of St. Lawrence. Together with the Great Lakes, the St. Lawrence system provides 9,500 miles (15,285 km) of navigable waterways. Unofficially, the entire Great LakesSt. Lawrence system has come to be known as the St. Lawrence Seaway. The seaway allows deep-draft ocean vessels access to the rich industrial and agricultural regions around the Great Lakes. The total seaway overcomes a 600-foot (183-metre) drop from Lake Superior to the Atlantic Ocean. Use is restricted to vessels of moderate size (by modern standards). There are a total of 12 Canadian and 66 U.S. ports that service the seaway. Bulk commodities account for most of the annual cargo tonnage of the St. Lawrence River section of the seaway. The leading product is cereal grain moving westward from farms on Canada's prairies and in the American Midwest; much of this grain is ultimately transshipped overseas. Another major commodity is iron ore from Quebec moving eastward on the canal for processing in foreign mills. Other significant commodities are coal (from American mines) and imported iron and steel. The navigation season of the seaway continues from early April to mid-December, or about 250 days.