Peace River

Peace River, largest branch of the Mackenzie River, in northwestern Alberta and eastern British Columbia, Canada. The river, formed at Williston Lake from the Finlay and Parsnip rivers, crosses the Rocky Mountains north and east and joins the Slave River at Lake Athabasca. It is about 1,000 mi (1,600 km) long. It was explored in 1792–93 by Sir Alexander Mackenzie.