The Mackenzie River: Canada's Longest River System

Location and Scale

The Mackenzie River is entirely in Canada—the country's longest river (1,738 km / 1,080 mi main stem; 4,241 km / 2,635 mi with headstreams).

Course

• Source: Great Slave Lake (Northwest Territories)
• Flows: Northwest through NWT, forms delta
• Mouth: Beaufort Sea (Arctic Ocean)

Key Features

• Basin: 1.8M km² (20% of Canada) — includes Peace, Athabasca, Liard rivers
• Named for: Alexander Mackenzie (1789 first European descent)
• Ice-covered: 6–8 months/year
• Transport: Summer barge traffic; winter ice roads
• Ecology: Critical for migratory birds, fish (whitefish, inconnu), beluga whales
• Indigenous: Dene, Inuvialuit, Métis homelands

Significance

Largest Canadian river by discharge; major freshwater input to Arctic Ocean; potential climate change indicator (permafrost thaw, flow changes).