St. Lawrence (river)

I

Introduction

St. Lawrence (river) (French Saint-Laurent), river in eastern North America. The chief outlet of the Great Lakes, the St. Lawrence flows northeast from Lake Ontario to the Gulf of St. Lawrence on the North Atlantic Ocean, a distance of 1,300 km (800 mi). As part of the St. Lawrence Seaway, a system of canals, locks, and dredged channels built to allow the passage of oceangoing vessels, the St. Lawrence River serves as a major water route to the interior of the United States and Canada, linking the Great Lakes with the Atlantic Ocean.

The total drainage area of the St. Lawrence River is 1,030,000 sq km (398,000 sq mi). Of this, some 750,000 sq km (290,000 sq mi) flows into the river through the Great Lakes, and 250,000 sq km (97,000 sq mi) drains directly to the St. Lawrence. The average flow of the St. Lawrence is 14,165 cu m per second (500,200 cu ft per second).

II

Description

The St. Lawrence River begins at the outlet of Lake Ontario and flows to the northeast. In its upper course, which includes the scenic Thousand Islands, the river forms the boundary between the province of Ontario and the state of New York. The river then widens into Lake Saint Francis, which serves for a short distance as the border between the provinces of Ontario and Québec, before flowing wholly in Québec for the remainder of its course. At Montréal the river expands to create Lake St.-Louis, and below Sorel it forms the much larger Lac Saint-Pierre. Below Québec the St. Lawrence broadens from a width of 3 km (2 mi) to 145 km (90 mi) at its mouth.

Ocean tides extend up the river for 800 km (500 mi) to the city of Trois-Rivières. The main tributaries of the St. Lawrence are the Ottawa, Saint-Maurice, and Saguenay rivers from the north, and the Richelieu, Saint-François, and Chaudière rivers from the south. The river is home to a great variety of fish, including sturgeon, smelt, and herring. Belugas (white whales) live near the Gulf of St. Lawrence.

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III

Economic Importance

The St. Lawrence Valley is one of the most densely populated parts of Canada, containing about 25 percent of the nation's population. The two largest cities in Québec province, Montréal and Québec City, lie on the north bank of the river. Montréal lies just below the Lachine Rapids, which were the upstream limit of navigation by oceangoing vessels before the completion, in 1959, of the St. Lawrence Seaway. Montréal rose to prominence as Canada's principal eastern seaport. Today large vessels must still stop at Montréal, while medium-sized oceangoing ships may continue to the Great Lakes. Icebreakers keep the ports of Montréal and Québec open year-round, but ice prevents navigation on the upper river from December to April.

Industry, especially aluminum smelting, paper milling, and general manufacturing, is the most important economic activity in the St. Lawrence Valley. The valley lowlands contain some fertile farmland, producing dairy goods, fruit, potatoes, and grain. Tourism is also important, especially in Montréal, the Thousand Islands, and Québec City. Hydroelectric power is generated in the area between Kingston, Ontario, and Montréal.

Industrial and municipal discharges in and around Trois-Rivières, Montréal, and Québec, as well as contamination on the Ottawa River, contribute some pollution to the St. Lawrence. However, because of the river's large volume of flow, the pollution concentrations are not as severe as those in many other rivers.

IV

History

The St. Lawrence Valley was once home to the Iroquois, Algonquin, Huron, Mohawk, Abenaki, and Montagnais peoples. The first European to visit the St. Lawrence River was the French explorer Jacques Cartier, in 1535. The first permanent European settlement on the St. Lawrence was established at the site of present-day Québec City by French explorer Samuel de Champlain in 1608. The river remained in French hands during the 17th and 18th centuries, when it served as the main route of the fur trade, transporting pelts from the Great Lakes and the St. Lawrence Valley for shipment to Europe. The British gained control of the region at the end of the French and Indian War in 1763. In 1867 Britain's Parliament passed the British North America Act, which formed the Dominion of Canada and included the St. Lawrence Valley. Today most of the valley lies within the province of Québec.

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