Mackenzie River

The Mackenzie River (French: Fleuve (de) Mackenzie; Slavey: Deh-Cho [tèh tʃʰò], literally big river; Inuvialuktun: Kuukpak [kuːkpɑk], literally great river) is a river in the Canadian boreal forest and tundra. It forms, along with the Slave, Peace, and Finlay, the longest river system in Canada, the second largest drainage basin of any North American river after the Mississippi.

The Mackenzie River flows through a vast, thinly populated region of forest and tundra entirely within the Northwest Territories in Canada, although its many tributaries reach into five other Canadian provinces and territories. The river's main stem is 1,738 kilometres (1,080 mi) long, flowing north-northwest from Great Slave Lake into the Arctic Ocean, where it forms a large delta at its mouth. Its extensive watershed drains about 20 percent of Canada. It is the largest river flowing into the Arctic from North America, and including its tributaries has a total length of 4,241 kilometres (2,635 mi), registering the 13th longest river system and 12th largest drainage basin on Earth.

The ultimate source of the Mackenzie River is Thutade Lake, in the Northern Interior of British Columbia. The Mackenzie valley is believed to have been the path taken by prehistoric peoples during the initial human migration from Asia to North America over 10,000 years ago, despite sparse evidence. The Inuvialuit, Gwich'in and other Indigenous peoples lived along the river for thousands of years. The river provided the major route into Canada's northern interior for early European explorers.