ROCKY MOUNTAINS, a vast system extending over three thousand miles from northern Mexico to Northwest Alaska, forms the western continental divide. The system varies from 70 to 400 miles wide and from 5,000 to 14,433 feet high. Mount Elbert in Colorado is its highest peak. The mountains uplifted about 63 million years ago during the Laramide Orogeny. During the last Ice Age, eleven thousand years ago, glaciers carved peaks and valleys.
Spanish explorers in Mexico were the first Europeans to see the Rockies, and Francisco Vásquez de Coronado was the first European to see the U.S. Rockies in 1540. Then came the French, hunting furs and new trade routes via the Great Lakes and Canadian streams. As early as 1743 members of the La Vérendrye family saw the "shining mountains" in the Wyoming region. The English followed, and pelt-hungry American trappers and traders came up the Missouri River and its tributaries, gathering beaver skins and later buffalo hides. These mountain men trail blazed the Central Rockies. In the years between 1825 and 1845 mountain men scoured the area for beaver, the difficult work made more so by weather, hunger, isolation, conflict with Native Americans, and grizzlies.
Although informal explorations of the Rockies occurred before the Louisiana Purchase (1803), what lay west of them was unknown. President Thomas Jefferson commissioned an expedition (1804–1805) led by Meriwether Lewis and William Clark to determine the commercial potential of northwestern natural resources and to investigate the possibility of a cross-continental water passage. Zebulon Pike led a similar expedition in the Southwest in 1806–1807. Reports from both expeditions were favorable. Following them came a long period of competition between American, Canadian, and British companies for control of the mountain fur trade. Another important explorer, Jedediah Smith, in 1823 rediscovered the forgotten South Pass across the continental divide, which allowed the settlement of Oregon and California, the Mormon trek of 1847, and the California gold rush of 1849. In 1850 the mountain man Jim Bridger discovered a shorter pass running south from the Great Basin, which became the route for overland mail, the Union Pacific Railroad, and Interstate 80.
Though the mountains and intervening plateaus were uninviting, gold discoveries during the 1850s and 1860s led to permanent settlement in the Rockies and eventually to the formation of mountain states. Agriculture followed mining in the West, helped by mountain snows that fed the rivers and the irrigation canals in the semiarid country to the east. Later the states undertook reservoir construction and water reclamation and diversion projects. The vital importance of mountain watershed protection led to national forest conservation, though lumbering became an important industry in the Rockies' more heavily wooded areas.
The federal government established four national parks in the Rocky Mountain region, Yellowstone National Park in Wyoming, Montana, and Idaho (1 March 1872), the world's greatest geyser area; Grand Teton National Park in Wyoming (26 February 1929); Glacier National Park in Montana (11 May 1910); and Rocky Mountain National Park in Colorado (26 January 1915).
Chronic, Halka. Pages of Stone. Seattle: Mountaineers, 1984– 1988.
McPhee, John. Rising from the Plains. New York: Farrar, Straus, Giroux, 1986.