Definitions of the Mackenzie River: "Mackenzie River: A river in northwest Canada, flowing northwest from the Great Slave Lake to the Arctic Ocean. 1120 miles (1800 km) long; with tributaries 2525 miles (4065 km) long." "Sir Alexander Mackenzie: 1755-1820, Scottish explorer and fur trader in Canada. He explored the Mackenzie River (1789) and was the first European to cross America north of Mexico (1793)." http: //www.dictionary.com/browse/mackenzie Abraham Rees; The Cyclopaedia: Or, Universal Dictionary of Arts, Sciences, and Literature; Vol 22; Longman, Hurst, Rees, Orme & Brown [etc]; 1819 Abraham Rees writes: "MACKENZIE's River, in Geography, on the northwest part of America, rises in Slave lake, runs a north-northwest course, and after receiving a number of large rivers, discharges itself into the north sea at Whale island, in north latitude 69 degrees 14 minutes, and between 130 degrees and 135 degrees west longitude, its course from Slave lake having been 780 miles. It derived its name from Mr McKenzie, who ascended this river in the summer of 1789. The Indian natives inhabiting the west side of the river from the Slave lake are the Strong-bow, Mountain, and Hare Indians; those on the east side the Beaver, Inland, Nathana, and Quarrelers."