St. Lawrence River Saint Lawrence River
Montréal-Est, Quebec
Great Lakes/St. Lawrence watershed
Etymology	Saint Lawrence of Rome
Location
Country	Canada, United States
Provinces	Ontario, Quebec
State	New York
Physical characteristics
Source	Lake Ontario
• location	Kingston, Ontario / Cape Vincent, New York
• coordinates	44°06′N 76°24′W / 44.100°N 76.400°W / 44.100; -76.400
• elevation	74.7 m (245 ft)
Mouth	Gulf of St. Lawrence / Atlantic Ocean
• location	Quebec, Canada
• coordinates	49°30′N 64°30′W / 49.500°N 64.500°W / 49.500; -64.500
• elevation	0 m (0 ft)
Length	500 km (310 mi) excluding the estuary. C. 928 km if included. (St. Lawrence River–Lake Ontario–Niagara–Lake Erie–Detroit–Lake St. Clair–St. Clair–Lake Huron–St. Marys River–Lake Superior–St. Louis–North River: 3,058 km)[1][2]
Basin size	1,344,200 km2 (519,000 sq mi)[3] (Pointe-des-Monts: 1,271,547.4 km2)[4]
Width
• average	1–5 km (0.62–3.11 mi)[5]
Depth
• minimum	2 m (6 ft 7 in) (Fluvial Section)[5]
• maximum	60 m (200 ft) (Quebec City)[5]
Discharge
• location	Pointe-des-Monts
• average	(Period: 1969–2023)17,600 m3/s (620,000 cu ft/s)[6]
• minimum	10,478 m3/s (370,000 cu ft/s)[6]
• maximum	33,085 m3/s (1,168,400 cu ft/s)[6]
Discharge
• location	Tadoussac
• average	(Period: 1962–1988)16,800 m3/s (590,000 cu ft/s)[7]
Discharge
• location	Quebec City
• average	(Period: 1968–2023)12,500 m3/s (440,000 cu ft/s)[6]
• minimum	8,600 m3/s (300,000 cu ft/s)[6]
• maximum	22,766 m3/s (804,000 cu ft/s)[6]
Discharge
• location	Montreal
• average	(Period: 1971–2000)10,063.3 m3/s (355,380 cu ft/s)[4]
Discharge
• location	Cornwall
• average	(1861–2019)7,060 m3/s (249,000 cu ft/s)[6]
Basin features
Progression	Gulf of St. Lawrence
River system	St. Lawrence River

v t e St. Lawrence River
Legend
Lake Ontario Wolfe Island Carleton Island Howe Island Grindstone Island Calumet Island Sugar Island Murray Isle Wellesley Island Ash Island Hill Island Thousand Islands Bridge Lake of the Isles Longue Vue Island Just Room Enough Island Heart Island Club Island Deer Island Zavikon Island Grenadier Island Tar Island Ironsides Island Oak Island Dark Island Oswegatchie River Ogdensburg–Prescott International Bridge Iroquois Lock Iroquois Dam Wiley-Dondero Canal Barnhart Island Long Sault Dam Eisenhower Lock Tunnel Eisenhower Lock Barnhart Island Bridge Moses-Saunders Power Dam Snell Lock Grasse River Galop Island Cornwall Island Seaway International Bridge Raquette River US CA St. Regis River Raisin River ON QC Lake Saint Francis Beauharnois Canal Grande-Île Saint Charles River Île-de-Salaberry Coteau Railway Bridge Monseigneur Langlois Bridge Larocque Bridge Île aux Vaches Barrage Juillet Saint-Louis-de-Gonzague Bridge Barrage Saint-Timothy Baie Bayard Centrale des Cèdres Serge-Marcil Bridge Barrage de la Pointe-du-Buisson Barrage de Pointe-des-Cascades Madeleine-Parent Bridge Pied-du-Canal Bridge Beauharnois Lock (upper) Beauharnois Generating Station Boulevard Edgar Hébert Bridge Beauharnois Lock (lower) Ottawa River Lake Saint-Louis Châteauguay River St. Lawrence Seaway Lachine Canal Saint-Laurent Railway Bridge Honoré Mercier Bridge Lachine Rapids Heron Island Côte Sainte Catherine Lock Champlain Bridge Ice Structure Champlain Bridge (under demolition) Samuel De Champlain Bridge Saint–Lambert Lock Victoria Bridge Notre Dame Island Saint Helen's Island Pont de la Concorde Lachine Canal Pont du Cosmos Montreal Metro Yellow Line Jacques Cartier Bridge Minirail Charron Island Louis-Hippolyte Lafontaine Bridge–Tunnel Sainte-Thérèse Island Rivière des Prairies Île Bouchard Sorel-Tracy–Berthierville Ferry Richelieu River Île de Grâce Maskinongé River Yamaska River Saint-François River Lake Saint Pierre Nicolet River Laviolette Bridge Saint-Maurice River Champlain River Batiscan River Sainte-Anne River Rivière du Moulin Portneuf River Jacques-Cartier River Rivière des Roches Charland River Rivière du Cap Rouge Pierre Laporte Bridge Quebec Bridge Lévis–Quebec City Ferry Saint-Charles River Île d'Orléans Île d'Orléans Bridge Boyer River Rivière des Mères Sainte-Anne-du-Nord River Isle-aux-Grues Île aux Coudres Malbaie River Rivière-du-Loup–Saint-Siméon Ferry Île aux Lièvres Verte Island L'Isle-Verte– Notre-Dame-des-Sept-Douleurs Ferry Saguenay River Trois Pistoles–Les Escoumins Ferry Île du Bic Rimouski River Rimouski–Forestville Ferry Rivière aux Outardes Tartigou River Manicouagan River Matane–Baie-Comeau Ferry Matane–Godbout Ferry Matane–Sept-Îles Ferry Matane River St. Lawrence Estuary Gulf of St. Lawrence Atlantic Ocean

The St. Lawrence River (French: Fleuve Saint-Laurent) is a large international river in the middle latitudes of North America connecting the Great Lakes to the North Atlantic Ocean. Its waters flow in a northeasterly direction from Lake Ontario to the Gulf of St. Lawrence, traversing Ontario and Quebec in Canada and New York in the United States. A section of the river demarcates the Canada–U.S. border.

As the primary drainage outflow of the Great Lakes Basin, the St. Lawrence has the second-highest discharge of any river in North America (after the Mississippi River) and the 16th-highest in the world. The estuary of St. Lawrence is often cited by scientists as the largest in the world. Significant natural landmarks of the river and estuary include the 1,864 river islands of the Thousand Islands, the endangered whales of Saguenay–St. Lawrence Marine Park, and the limestone monoliths of the Mingan Archipelago.

Long a transportation route to Indigenous peoples, the St. Lawrence River has played a key role in the history of Canada and in the development of cities such as Montreal and Quebec City. The river remains an important shipping route as the backbone of the St. Lawrence Seaway, a lock and canal system that enables world marine traffic to access the inland ports of the Great Lakes Waterway.

The river has been called a variety of names by local First Nations. Beginning in the 16th century, French explorers visited what is now Canada and gave the river names such as the Grand fleuve de Hochelaga and the Grande rivière du Canada,^[8] where fleuve and rivière are two French words (fleuve being a river that flows into the sea).

The river's present name has been used since 1604 when it was recorded on a map by Samuel de Champlain^[8] Champlain opted for the names Grande riviere de sainct Laurens and Fleuve sainct Laurens in his writings, supplanting the earlier names.^[8] In contemporary French, the name is rendered as the fleuve Saint-Laurent. The name Saint-Laurent (Saint Lawrence) was originally applied to the eponymous bay by Jacques Cartier upon his arrival into the region on the 10th of August feast day for Saint Lawrence in 1535.^[8]

Indigenous people use the following names:

• Innu-aimun, the language of Nitassinan, refer to it as Wepistukujaw Sipo/Wepìstùkwiyaht sīpu.^[8][9]
• the Abenaki call it Moliantegok/Moliantekw ("Montréal River"),^[8] Kchitegw/Ktsitekw/Gicitegw ("Great River"),^[9] or Oss8genaizibo/Ws8genaisibo/Wsogenaisibo ("River of the Algonquins").^[9]
• in Mohawk language it is Roiatatokenti, Raoteniateara,^[8] Ken’tarókwen,^[10] or Kaniatarowanénhne.^[11]
• Tuscarora people call it Kahnawáˀkye or Kaniatarowanenneh ("Big Water Current").^[12]
• Algonquin people call it "the Walking Path" or Magtogoek,^[8][13] or Kitcikanii sipi, the "Large Water River".^[9][14]
• the Huron-Wendat Nation call it Lada8anna or Laooendaooena'.^[9]
• the Atikamekw of Nitaskinan refer to it as Micta sipi ("Huge River").

In winter, the St. Lawrence River begins producing ice in December, with the formation of ice cubes between Montreal and Quebec City. The prevailing winds and currents push this ice towards the estuary,^[15] and it reaches the east of Les Méchins at the end of December. Ice covers the entire Gulf of St. Lawrence in January and February.

Ice helps navigation by preventing the formation of waves, and therefore spray, and prevents the icing of ships.^[16]

With the draining of the Champlain Sea, due to a rebounding continent from the Last Glacial Maximum, the St. Lawrence River was formed. The Champlain Sea lasted from about 13,000 years ago to about 10,000 years ago and was continuously shrinking during that time, a process that continues today.^[17][18] The head of the St. Lawrence River, near Lake Ontario, is home to the Thousand Islands.^[19]

Today, the St. Lawrence River begins at the outflow of Lake Ontario and flows adjacent to Gananoque, Brockville, Morristown, Ogdensburg, Massena, Cornwall, Montreal, Trois-Rivières, and Quebec City before draining into the Gulf of St. Lawrence, often given as the largest estuary in the world.^[20] The estuary begins at the eastern tip of Île d'Orléans, just downstream from Quebec City.^[7] The river becomes tidal around Quebec City.^[21]

The St. Lawrence River runs 3,058 kilometres (1,900 mi) from the farthest headwater to the mouth and 1,197 km (743.8 mi) from the outflow of Lake Ontario. These numbers include the estuary; without the estuary, the length from Lake Ontario is c. 500 km (c. 300 mi). The farthest headwater is the North River in the Mesabi Range at Hibbing, Minnesota. Its drainage area, which includes the Great Lakes, the world's largest system of freshwater lakes, is 1,344,200 square kilometres (518,998.5 sq mi), of which 839,200 km² (324,016.9 sq mi) is in Canada and 505,000 km² (194,981.6 sq mi) is in the United States. The basin covers parts of Ontario and Quebec in Canada, parts of Minnesota, Wisconsin, Illinois, Indiana, Ohio, Pennsylvania, New York, Vermont, and nearly the entirety of the state of Michigan in the United States. The average discharge below the Saguenay River is 16,800 cubic metres per second (590,000 cu ft/s). At Quebec City, it is 12,101 m³/s (427,300 cu ft/s). The average discharge at the river's source, the outflow of Lake Ontario, is 7,410 m³/s (262,000 cu ft/s).^[7]

The St. Lawrence River includes Lake Saint Francis at Salaberry-de-Valleyfield, Lake Saint-Louis south of Montreal and Lake Saint Pierre east of Montreal. It encompasses four archipelagoes: the Thousand Islands chain near Alexandria Bay, New York and Kingston, Ontario; the Hochelaga Archipelago, including the Island of Montreal and Île Jésus (Laval); the Lake St. Pierre Archipelago (classified a biosphere world reserve by the UNESCO in 2000)^[22] and the smaller Mingan Archipelago. Other islands include Île d'Orléans near Quebec City and Anticosti Island north of the Gaspé. It is the second longest river in Canada.

Lake Champlain and the Ottawa, Richelieu, Saint-Maurice, Saint-François, Chaudière and Saguenay rivers drain into the St. Lawrence.

The St. Lawrence River is in a seismically active zone where fault reactivation is believed to occur along late Proterozoic to early Paleozoic normal faults related to the opening of the Iapetus Ocean. The faults in the area are rift-related and comprise the Saint Lawrence rift system.

According to the United States Geological Survey, the St. Lawrence Valley is a physiographic province of the larger Appalachian division, containing the Champlain section.^[23] However, in Canada, where most of the valley is, it is instead considered part of a distinct St. Lawrence Lowlands physiographic division, and not part of the Appalachian division at all.^[24]

The source of the North River in the Mesabi Range in Minnesota (Seven Beaver Lake) is considered to be the source of the St. Lawrence River. Because it crosses so many lakes, the water system frequently changes its name. From source to mouth, the names are:

The St. Lawrence River also passes through Lake Saint-Louis and Lake Saint-Pierre in Quebec.

Looking downstream: Quebec City (left), St. Lawrence River, Île d'Orléans (center), Lévis (right), Laurentian Mountains (background).

The St. Lawrence River and the largest tributaries of the Great Lakes.

The St. Lawrence River tributaries are listed upstream from the mouth. The major tributaries of the inter-lake sections are also shown, as well as the major rivers that flow into the Great Lakes. Great Lakes tributaries are listed in alphabetical order.

The list includes all tributaries with a drainage area of at least 1,000 square kilometres and an average flow of more than 10 cubic metres per second.

The diversity of the St. Lawrence River includes:^[27]

• 19 species of marine mammals
• More than 230 species of birds
• Nearly 35 species of amphibians and reptiles
• 200 species of freshwater and aquatic fish salty (including 19 sharks and rays)
• 2200 invertebrates in the estuary and its gulf (sponges, jellyfish, corals, crustaceans, etc.)
• Nearly 2000 vascular plants^[28]

Large marine mammals travel in all the seas of the earth, the research and observations of these giants concern fishermen and shipping industry, exercise a fascination and a keen interest for laymen and, subjects of endless studies for scientists from Quebec, Canada and around the world.^[29][30][31]

Thirteen species of cetaceans frequent the waters of the estuary and the Gulf of St. Lawrence:^[32]

1. Northern bottlenose whale
2. Delphinapterus leucas (Beluga Whale)^[33][34]
3. Sperm whale
4. Atlantic white-sided dolphin
5. White-beaked dolphin
6. Orca
7. Long-finned pilot whale
8. Phocoena phocoena (Harbour Porpoise)
9. North Atlantic right whale^[35]
10. Common minke whale
11. Blue whale^[36]
12. Humpback whale
13. Fin whale

Flowing through and adjacent to numerous Indigenous homelands, the river was a primary thoroughfare for many peoples. Beginning in Dawnland at the Gulf of St. Lawrence, the river borders Mi'kma'ki^[37] in the South (what is today known as the Canadian Maritimes), and Nitassinan in the North, the national territory of the Innu people.^[38] On the south shore beyond the Mi'kmaw district of Gespe'gewa'ki,^[37] the river passes Wolastokuk (the Maliseet homeland), Pαnawαhpskewahki (the Penobscot homeland), and Ndakinna (the Abenaki homeland).^[39] Continuing, the river passes through the former country of the St. Lawrence Iroquois and then three of the six homelands of the Haudenosaunee: the Mohawk or Kanienʼkehá꞉ka, the Oneida or Onyota'a:ka, and the Onondaga or Onöñda’gaga’.^[39]

In the early 17th century, the Huron-Wendat Nation migrated from their original country of Huronia to what is now known as Nionwentsïo centred around Wendake.^[40][41] Nionwentsïo occupies both the north and south shores of the river,^[40] overlapping with Nitassinan and the more western Wabanaki or Dawnland countries.^[39] Adjacent on the north shore is the Atikamekw territorial homeland of Nitaskinan^[42][43] and, upstream, the further reaches of Anishinaabewaki, specifically the homelands of the Algonquin and Mississauga Nations.^[39]

The Norse explored the Gulf of St. Lawrence in the 11th century and were followed by fifteenth- and early sixteenth-century European mariners, such as John Cabot, and the brothers Gaspar and Miguel Corte-Real. The first European explorer known to have sailed up the St. Lawrence River itself was Jacques Cartier. At that time, the land along the river described as "about two leagues, a mountain as tall as a heap of wheat" was inhabited by the St. Lawrence Iroquoians. During Cartier's second voyage in 1535, because Cartier arrived in the estuary on Saint Lawrence's feast day 10 August, he named it the Gulf of Saint Lawrence.^{[44] [45]}

The St. Lawrence River is today partly within the U.S. and as such is that country's sixth oldest surviving European place-name.^[46]

The earliest regular Europeans in the area were the Basques, who came to the St Lawrence Gulf and River in pursuit of whales from the early 16th century. The Basque whalers and fishermen traded with indigenous Americans and set up settlements, leaving vestiges all over the coast of eastern Canada and deep into the St. Lawrence River. Basque commercial and fishing activity reached its peak before the Armada Invencible's disaster (1588), when the Basque whaling fleet was confiscated by King Philip II of Spain. Initially, the whaling galleons from Labourd were not affected by the Spanish defeat.

Until the early 17th century, the French used the name Rivière du Canada to designate the St. Lawrence upstream to Montreal and the Ottawa River after Montreal. The St. Lawrence River served as the main route for European exploration of the North American interior, first pioneered by French explorer Samuel de Champlain.

Control of the river was crucial to British strategy to capture New France in the Seven Years' War. Having captured Louisbourg in 1758, the British sailed up to Quebec the following year thanks to charts drawn up by James Cook. British troops were ferried via the St. Lawrence to attack the city from the west, which they successfully did at the Battle of the Plains of Abraham. The river was used again by the British to defeat the French siege of Quebec under the Chevalier de Lévis in 1760.

In 1809, the first steamboat to ply its trade on the St. Lawrence was built and operated by John Molson and associates, a scant two years after Fulton's steam-powered navigation of the Hudson River. The Accommodation with ten passengers made her maiden voyage from Montreal to Quebec City in 66 hours, for 30 of which she was at anchor. She had a keel of 75 feet, and a length overall of 85 feet. The cost of a ticket was eight dollars upstream, and nine dollars down. She had berths that year for twenty passengers.^[47] Within a decade, daily service was available in the hotly-contested Montreal-Quebec route.^[48]

Because of the virtually impassable Lachine Rapids, the St. Lawrence was once continuously navigable only as far as Montreal. Opened in 1825, the Lachine Canal was the first to allow ships to pass the rapids. An extensive system of canals and locks, known as the St. Lawrence Seaway, was officially opened on 26 June 1959 by Elizabeth II (representing Canada) and President Dwight D. Eisenhower (representing the United States). The Seaway (including the Welland Canal) now permits ocean-going vessels to pass all the way to Lake Superior.^[49]

During the Second World War, the Battle of the St. Lawrence involved submarine and anti-submarine actions throughout the lower St. Lawrence River and the entire Gulf of St. Lawrence, Strait of Belle Isle and Cabot Strait from May to October 1942, September 1943, and again in October and November 1944. During this time, German U-boats sank several merchant marine ships and three Canadian warships.

In the late 1970s, the river was the subject of a successful ecological campaign (called "Save the River"), originally responding to planned development by the United States Army Corps of Engineers. The campaign was organized, among others, by Abbie Hoffman.^[50]

• Gatien Lapointe, Ode au Saint-Laurent, Éditions du Jour, Montréal, 1963, Paradis, A. (1963), report, 3 pages.^[51]
• The river was the setting for the Canadian television drama series Seaway.
• It is the namesake of Saint-Laurent Herald.
• In 1980, Jacques Cousteau filmed Cries from the Deep and St. Lawrence: Stairway to the Sea.^[52]
• The 1993 Canadian animated short film The Mighty River was about the river.
• The novel and film Black Robe are set primarily on the St. Lawrence River during the 17th century.
• The 1941 children's book Paddle-to-the-Sea, and the film Paddle to the Sea, involve passage through the St. Lawrence River.

Wikimedia Commons has media related to Saint Lawrence River.

• Fur Trade Canoe Routes of Canada/Then and Now, 1969, Eric W. Morse, M.A.;F.R.G.S, 121 p.
• The Saint Lawrence Its Basin & Border-Lands, 1905, Dr. S. E. Dawson, 584 p.
• St. Lawrence Parks Commission (Ontario)
• Great Lakes St. Lawrence Seaway System
• Radio Aids to Marine Navigation 2024, Radio Aids to Marine Navigation 2024, (Atlantic, St. Lawrence, Great Lakes, Lake Winnipeg, Arctic and Pacific) Fisheries and Oceans Canada, 298 pages
• Safe Passage: Aids to Navigation on the St. Lawrence – Historical essay, illustrated with drawings and photographs
• Annotated Bibliography on St. Lawrence County and Northern New York region.
• International St. Lawrence River Board of Control
• Saint Lawrence River, The Canadian Encyclopedia
• Watch the Jacques Cousteau documentary, St. Lawrence: Stairway to the Sea
• Timing and position of late Wisconsinan ice-margins on the upper slope seaward of Laurentian Channel David J. W. Piper et Adam Macdonald, 2001, 11 page

[[Category:Rivers