Mackenzie River
in North America, a stream having its origin, as the Athabasca, in a Rocky Mountain lake in British Columbia, flowing over 600 miles to Lake Athabasca, and 240 as the Slave river to Great Slave Lake, where it assumes the name of Mackenzie river, conveying the waters of the Great Slave Lake to the Arctic Ocean at Mackenzie Bay, after a final course of 1,045 miles, making a total river system of nearly 2,525 miles. It drains an area of little less than 600,000 square miles. The mouth of the river is closed from October to June by ice. The Mackenzie district itself is desolate and unfit for colonization; but its great tributaries, the Laird and the Peace and Athabasca rivers, drain an immense fertile country, with abundance of petroleum (the fields have more than once been reported to be the largest in the world), and some coal and lignite. The Mackenzie received its name from Sir Alexander Mackenzie, by whom it was discovered and first navigated in 1789. Sir John Franklin descended it in 1825.