St. Lawrence River

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, pronounced [flœv sɛ̃ lɔʁɑ̃]) 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.