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 (4,800 kilometers) 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 80 million to 55 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.

Of the 100 highest major peaks of the Rocky Mountains, 78 (including the 30 highest) are located in Colorado, ten in Wyoming, six in New Mexico, three in Montana, and one each in Utah, British Columbia, and Idaho. Of the 50 most prominent summits of the Rocky Mountains, 12 are located in British Columbia, 12 in Montana, ten in Alberta, eight in Colorado, four in Wyoming, three in Utah, three in Idaho, and one in New Mexico. 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.