Rocky Mountains or Rockies, great chain of rugged mountain ranges in western North America, extending from central New Mexico to northeastern British Columbia, a distance of about 3220 km (about 2000 mi). The Great Basin and the Rocky Mountain Trench, a valley running from northwestern Montana to northern British Columbia, border the Rockies on the east by the Great Plains and on the west. The Rocky Mountains form part of the Great, or Continental, Divide, which separates rivers draining into the Atlantic or Arctic oceans from those flowing toward the Pacific Ocean. The Arkansas, Colorado, Columbia, Missouri, Rio Grande, Saskatchewan, and Snake rivers rise in the Rockies.
             The Rockies may be divided into four principal sections-Southern, Central, Northern, and Canadian. The Southern Rockies, which include the system's broadest and highest regions, extend from central New Mexico, through Colorado, to the Great Divide, or Wyoming, Basin, in southern Wyoming. This section, which encompasses Rocky Mountain National Park, is composed chiefly of two northern-southern belts of mountain ranges with several basins, or parks, between the belts. The component parts include the Sanger de Crisco and Laramie mountains and the Front Range, in the east, and the San Juan Mountains and the Swatch and Park ranges, in the west. The Southern Rockies include the chain's loftiest point, Mount Elbert (4399 m/14,433 ft high), in central Colorado. More than 50 other peaks of the Rockies rising above 4267 m (14,000 ft) are in Colorado; these include Longs Peak (4345 m/14,255 ft high) and Pikes Peak (4301 m/14,110 ft high).
             The Central Rockies are in northeastern Utah, western Wyoming, eastern Idaho, and southern Montana. They encompass the Bighorn; Bear tooth, and Unite Mountains and the Absaroka, Wind River, Salt River, Teton, Snake River, and Wasatch ranges. The Unite Mountains are the only major portion of the Rockies that extends east west rather than nor...