MACKENZIE MOUNTAINS

northern extension of the Rocky Mountains, in the Yukon and in Inuvik and Fort Smith regions (Northwest Territories), Canada. The range extends northwestward from the British Columbia border for approximately 500 miles (800 km) to the Peel River plateau and the Porcupine River basin. The mountains serve as the watershed for the basins of the Mackenzie River (east) and Yukon River (west) and are the source for the Pelly River, a headstream of the Yukon. The Franklin Mountains, paralleling the eastern bank of the Mackenzie River for about 300 miles (480 km), are sometimes regarded as part of the range. The highest peak is Mount Sir James MacBrien (9,061 feet ), and many others, including Keele and Dome peaks and Mounts Hunt, Sidney Dodson, and Ida, reach elevations exceeding 8,000 feet (2,400 m). Named for Sir Alexander Mackenzie, who explored the Mackenzie River in 1789, the mountains were generally ignored until World War II, when an oil field at Norman Wells on the Mackenzie River was developed. A 400-mile (645-kilometre) pipeline was built to Whitehorse, Yukon Territory, to fuel U.S. military bases in the Pacific Northwest. After the war, oil production was confined to local needs. The Mackenzie Mountains Game Preserve was established in 1938, and Nahanni National Park was established in 1972 in the southern part of the range.