Imagine a region with a skyline of jagged peaks that reach higher skyward than anywhere else in the continental United States. This is a place of broad plains and wide, rapid-running rivers, where everything is giant-sized. This is the Intermountain West, and the mountains are the Rockies.
Nothing is small in the Intermountain West. These mountains make mountains elsewhere in the country (like the eastern seaboard) seem more like hills. All of the large rivers that flow eastward across the Great Plains and into the Mississippi originate in the Intermountain West. Rivers such as the Missouri, the Arkansas, the Red, the Canadian, the Platte, and the Rio Grande all begin in the Rocky Mountains. So do the two great rivers of the west — the Colorado in the southwest and the Columbia (which rises in the Canadian Rockies) in the northwest.