Rocky Mountains. The Rocky Mountains, also known as the Rockies, are a major mountain range and the largest mountain system in North America. The Rocky Mountains stretch 3,000 miles in straight-line distance from the northernmost part of western Canada, to New Mexico in the southwestern United States. Depending on differing definitions between Canada and the U.S., its northern terminus is located either in northern British Columbia's Terminal Range south of the Liard River and east of the Trench, or in the northeastern foothills of the Brooks Range / British Mountains that face the Beaufort Sea coasts between the Canning River and the Firth River across the Alaska-Yukon border. Its southernmost point is near the Albuquerque area adjacent to the Rio Grande rift and north of the Sandia-Manzano Mountain Range. Being the easternmost portion of the North American Cordillera, the Rockies are distinct from the tectonically younger Cascade Range and Sierra Nevada, which both lie farther to its west. The Rockies formed 55 million to 80 million years ago during the Laramide orogeny, in which a number of plates began sliding underneath the North American plate. The angle of subduction was shallow, resulting in a broad belt of mountains running down western North America. Since then, further tectonic activity and erosion by glaciers have sculpted the Rockies into dramatic peaks and valleys. At the end of the last ice age, humans began inhabiting the mountain range. After explorations of the range by Europeans, such as Sir Alexander Mackenzie, and Anglo-Americans, such as the Lewis and Clark Expedition, natural resources such as minerals and fur drove the initial economic exploitation of the mountains, although the range itself never experienced a dense population. Most of the highest summits of the Rocky Mountains are in Colorado, with that state having an average elevation in excess of 2,000 metres. Public parks and forest lands protect much of the mountain range, and they are popular tourist destinations, especially for hiking, camping, mountaineering, fishing, hunting, mountain biking, snowmobiling, skiing, and snowboarding. The Santa Fe Mountains at the southern end of the Rockies as seen from the Sandia Crest in New Mexico The summits of the Teton Range in Wyoming The name of the mountains is a translation of an Amerindian Algonquian name, specifically Cree, literally rocky mountain. The first mention of their present name by a European was in the journal of Jacques Legardeur de Saint-Pierre in 1752, where they were called. Another name given to the place by the Cree is. See also: List of rivers of the Rocky Mountains The Rocky Mountains are the easternmost portion of the expansive North American Cordillera. They are often defined as stretching from the Liard River in British Columbia south to the headwaters of the Pecos River, a tributary of the Rio Grande, in New Mexico. The Rockies vary in width from 110 to 480 kilometres. The Rocky Mountains contain the highest peaks in central North America. The range's highest peak is Mount Elbert in Colorado at 4,401 metres above sea level. Mount Robson in British Columbia, at 3,954 m, is the highest peak in the Canadian Rockies. Mount Robson in British Columbia The eastern edge of the Rockies rises dramatically above the Interior Plains of central North America, including the Sangre de Cristo Mountains of New Mexico and Colorado, the Front Range of Colorado, the Wind River Range and Big Horn Mountains of Wyoming, the Absaroka-Beartooth ranges and Rocky Mountain Front of Montana and the Clark Range of Alberta. Central ranges of the Rockies include the La Sal Range along the Utah-Colorado border, the Abajo Mountains and Henry Mountains of Southeastern Utah, the Uinta Range of Utah and Wyoming, and the Teton Range of Wyoming and Idaho. The western edge of the Rockies includes ranges such as the Wasatch near Salt Lake City, the San Juan Mountains of New Mexico and Colorado, the Bitterroots along the Idaho-Montana border, and the Sawtooths in central Idaho. The Great Basin and Columbia River Plateau separate these subranges from distinct ranges further to the west. In Canada, the western edge of the Rockies is formed by the huge Rocky Mountain Trench, which runs the length of British Columbia from its beginning as the Kechika Valley on the south bank of the Liard River, to the middle Lake Koocanusa valley in northwestern Montana. The Canadian Rockies are defined by Canadian geographers as everything south of the Liard River and east of the Rocky Mountain Trench, and do not extend into Yukon, Northwest Territories or central British Columbia.