Richelieu (river, Canada)

Richelieu (river, Canada), river in southern Québec province, Canada, 338 km (210 mi) long. It issues from the northern end of Lake Champlain, near the United States border, and flows north to the St. Lawrence River, near the city of Sorel and Lake Saint-Pierre. The surrounding valley was originally inhabited by the Algonguin, Iroquois, and Huron. The river was navigated by French explorer Samuel de Champlain in 1609. In 1642, the river was named after Cardinal Richelieu of France (see Richelieu, Armand Jean du Plessis, Duc de). It was an important military route during the French and Indian War (1756-1763), the American Revolution (1775-1783), and the War of 1812. Economically important in the 19th century, the Richelieu's commercial traffic eventually declined with the construction of railway lines between Montréal and the United States.