A Mountain Range Across a Continent
The Rocky Mountains, often simply called the Rockies, stretch all the way from western Canada down to the state of New Mexico in the southwestern United States. From end to end, the range runs roughly 4,800 kilometres, making it the largest mountain system in North America.
Many Ranges in One
The Rockies are not a single ridge but a vast system made up of many separate mountain ranges grouped together. They pass through several Canadian provinces and a number of U.S. states. Because they cover such a long distance from north to south, the scenery, climate, and wildlife vary greatly from one end of the Rockies to the other.
The Backbone of the Continent
The Rocky Mountains play a special role in the geography of North America. Running along their crests is the Continental Divide, an invisible line that separates which way water flows: rivers on one side ultimately drain toward one ocean, and rivers on the other side drain toward another. For this reason the Rockies are sometimes called the backbone of the continent.
Source
This article was written using information from Wikipedia.