The Rocky Mountains

The Rocky Mountains (or "Rockies") are the great mountain range of western North America, running for nearly 5,000 km from northern British Columbia in Canada down to New Mexico in the United States. They are younger than they look and contain some of the most famous national parks in the world, including Yellowstone, the Grand Tetons, Banff and Jasper.

• Lengthapprox. 4,800 kmSecond longest range in the Americas
• Countries2Canada and the United States
• Highest peakMount Elbert4,401 m, in Colorado
• Ageapprox. 80 million yearsYounger than the Appalachians but older than the Andes' current uplift
• Famous parksYellowstone, BanffPlus Grand Teton, Jasper, Glacier and others
• Famous animalsGrizzly bears, bisonPlus moose, elk, wolves and bighorn sheep

The Rockies compared to other ranges

Length (km)

Andes7,000

Rockies4,800

Himal.2,400

Alps1,200

The Rockies are the second-longest mountain range in the Americas after the Andes, and the third longest in the world.

What are the Rocky Mountains?

The Rocky Mountains are not a single straight chain but a series of ranges of different ages and shapes, all linked together. The northernmost section runs through northern British Columbia and the Yukon in Canada. The Canadian Rockies through Alberta and BC are famous for their dramatic glaciers and clear blue lakes. The US Rockies run through Montana, Idaho, Wyoming, Utah, Colorado and New Mexico, where the range gradually gives way to the deserts of the southwest.

Yellowstone and the supervolcano

One of the most spectacular parts of the Rockies is Yellowstone National Park, the first national park established anywhere in the world (in 1872). Yellowstone sits on top of a giant supervolcano, a huge magma chamber 8 km underground. Surface water that trickles down through the rock gets superheated and erupts back to the surface as geysers (including the famous Old Faithful) and hot springs. Yellowstone has more than half of all the geysers on Earth.

Fact The Continental Divide of the Americas runs along the crest of the Rockies. Rainwater that falls on the western slopes flows to the Pacific Ocean. Rainwater that falls on the eastern slopes flows to the Atlantic or the Arctic. A single raindrop can land on the wrong side of a ridge by less than a metre and end up in a completely different ocean.

Wildlife of the Rockies

The Rocky Mountains are home to most of the famous large North American wildlife. Grizzly bears and black bears both live in the range, especially in the wilder northern sections. American bison survive in Yellowstone in the only continuously wild herd in the United States. Wolves, hunted to extinction in Yellowstone by the 1920s, were famously reintroduced in 1995 and have transformed the park's ecology. Moose, elk, bighorn sheep and mountain goats all live in the high country.

National parks

The Rockies contain some of the most spectacular national parks on Earth. In the United States: Yellowstone, Grand Teton, Glacier (Montana), and Rocky Mountain (Colorado). In Canada: Banff (the first Canadian national park, established 1885), Jasper, Yoho and Kootenay, all linked together in a giant UNESCO World Heritage Site. The parks attract millions of visitors a year and protect huge areas of wilderness.

Did you know? The famous song "Home on the Range" (the unofficial anthem of the American West) was first written down in 1873 and refers directly to the Rocky Mountain area: "Where the deer and the antelope play..."

Deeper dive: Laramide orogeny, the Continental Divide and the Greater Yellowstone Ecosystem

The Rockies were built mainly during the Laramide orogeny, a mountain-building event that lasted from approx. 80 million years ago to approx. 35 million years ago. Unusually for a mountain range, the Laramide was caused by a shallow-angle subduction: an oceanic plate (the Farallon plate) was being pushed under North America at an unusually flat angle, causing compression and uplift far inland from the actual plate boundary. This produced the Rockies hundreds of kilometres inland from the Pacific coast. Volcanic activity continued for many millions of years after the main mountain-building was over, producing the volcanic features that still define areas like Yellowstone.

The Continental Divide of the Americas runs along the highest crest of the Rocky Mountains all the way from the Bering Strait to the southern tip of South America. North of Mexico it follows the Rockies; south of Mexico it follows the Andes. The Divide separates the watersheds of the Pacific Ocean (to the west) from those of the Atlantic and Arctic Oceans (to the east). The exact line is sometimes a knife-edge ridge that hikers can straddle, putting one foot in the Pacific watershed and the other in the Atlantic watershed. In Glacier National Park there is one isolated lake called Triple Divide Peak whose waters split three ways into the Pacific, the Atlantic and the Arctic.

The Greater Yellowstone Ecosystem is one of the largest nearly-intact temperate ecosystems on Earth, covering approx. 90,000 square km across Yellowstone, Grand Teton, and several surrounding national forests. It is one of the few places in the lower 48 US states with the full pre-European-settlement large-mammal community: bison, elk, moose, mule deer, white-tailed deer, pronghorn antelope, mountain goats, bighorn sheep, grizzly bears, black bears, wolves, coyotes, mountain lions, lynx, wolverines, river otters, beavers, and many smaller species. The 1995 wolf reintroduction is the most studied trophic cascade in modern ecology, with documented effects on elk populations, river vegetation, beaver activity, and many other parts of the ecosystem.

For the most famous part of the Rockies, see Yellowstone. The longer chain to the south is the Andes.