Physical features

The Rocky Mountains are more than 3,000 miles (4,800 kilometers) long and 300 miles (480 kilometers) wide in some places. They cover an area of about 300,000 square miles (777,000 square kilometers). The mountains rise sharply from the Great Plains to the east. Most of them were formed between 65 million and 35 million years ago.

The Rocky Mountains include at least 100 separate ranges. The ranges can be grouped into several large sections. The Northern Rockies run through British Columbia and Alberta in Canada and through Montana, Idaho, and Washington in the United States. The Mackenzie and Selwyn ranges, farther to the north in Canada, are often included in the Northern Rockies as well. The Middle Rockies are in Wyoming, Utah, and Idaho. The Wyoming Basin, an area of lower mountains, separates the Middle Rockies from the Southern Rockies. The Southern Rockies are mainly in Colorado and New Mexico. Mount Elbert, the highest of the Rockies at 14,433 feet (4,399 meters), is in this area. Pikes Peak, in Colorado's Front Range, is a bit lower at 14,110 feet (4,301 meters). However, it is famous because its summit can be reached by road, trail, or railway.

The Brooks Range of Alaska is sometimes considered part of the Rocky Mountains as well. It extends the Rockies in an east-west arc from the Canadian border across northern Alaska. At the southern end of the Rockies is the mountainous Colorado Plateau, in the region where Utah, Colorado, New Mexico, and Arizona meet.

Through most of Canada and the United States, the Rockies form the North American Continental Divide. The Continental Divide is the ridge that separates the waterways that flow eastward, toward the Atlantic and Arctic oceans, from those that flow westward, toward the Pacific. The most important river on the eastern side is the Missouri, which empties through the Mississippi River into the Gulf of Mexico. Major western rivers include the Fraser in Canada, the Columbia in the Pacific Northwest of the United States, and the Colorado in the southwestern United States. Some water stays on the mountains year after year in the form of ice masses called glaciers. Glaciers are found in the Middle and Northern Rockies.

Climate

The climate in the Rockies varies widely. In general, there is more rain and snow in the north than in the south. Some parts of the south are desertlike. The far north is cold, with Arctic conditions. Temperatures generally increase toward the south, but the climate remains cool at high elevations. In summer, only a short distance may separate warm foothills from frosty peaks. Overall, the Rocky Mountain climate has been getting warmer over the years because of the process called global warming. An example of the effects of global warming can be seen in Glacier National Park in Montana. Because of melting, the park's biggest glaciers are only one third as large as they were in the mid–19th century.

Plants and animals

The plant life of different parts of the Rockies depends on elevation, climate, and other conditions. The trees of the middle elevations include aspen, white pine, and Douglas fir. Higher up are western hemlock, lodgepole pine, western red cedar, and varieties of spruce. In the far northern Rockies, dwarfed willows grow. Above a certain elevation—called the timberline—there are no trees, mostly because of the harsh climate. The vegetation of this area consists mainly of low, flowering plants. Wildflowers of the forests and high meadows include columbine, larkspur, and Indian paintbrush. Sagebrush is common in the valleys.

The Rockies support many different kinds of large animals and birds. Among the mammals are bighorn sheep, mountain goats, mountain lions, American elk (wapiti), caribou, and grizzly bears. Coyotes roam freely throughout the chain. Wolves, once almost killed off by humans, were reintroduced into Yellowstone National Park in the Rockies during the 1990s. The bald eagle, golden eagle, peregrine falcon, and other birds of prey soar above the mountains.

People

Native Americans may have first arrived in the Rocky Mountain region as early as 12,000 years ago. However, fewer groups lived there than on the Great Plains or the Pacific coast. Among the Native Americans of the northern mountains were the Kootenai of what is now Canada and the Shoshone, Coeur d'Alene, and Flathead of what is now the United States. The Ute, Navajo, Hopi, Pueblo and other groups lived farther south. The first non–Native Americans to enter the territory were the Spanish, who arrived in the Southwest in the 16th century. By the early 19th century the Native Americans and the Europeans were often fighting over land. Many Native Americans now live on reservations established throughout the region. The urban population of the Rockies is concentrated at the base of mountains, along railways, or in river valleys.

Economy

The Rocky Mountains are rich in minerals. Copper, gold, silver, lead, and zinc are among the valuable metals found in large mountain mines. Energy resources of the Rockies include petroleum and natural gas. Oil shale—a type of rock that yields petroleum when heated—is common. The mountains and the Great Plains to the east have the largest reserves of coal in the Western Hemisphere.

Spectacular scenery attracts many tourists to the Rockies. The splendor of the Yellowstone area of Wyoming inspired the U.S. government to create the country's first national park there. Yellowstone National Park is now listed as a World Heritage site by the United Nations, as are Jasper, Banff, Yoho, and Kootenay national parks in Canada. Other popular national parks in the region are Glacier in Montana, Grand Teton in Wyoming, and Rocky Mountain in Colorado.

Little farming takes place in the Rockies, but hardy crops such as potatoes and wheat are grown in some areas. Cattle and sheep graze in valleys and mountain meadows. In Canada, the Rocky Mountain forests produce much of the nation's timber. In the United States, however, most of the forests have been set aside for preservation. Recreation is the main source of revenue in the U.S. forests.

Study and exploration

With their rough terrain and harsh weather, the Rocky Mountains were a challenge for early explorers. As a result, they were one of the last parts of North America to be explored by Europeans. In the 17th and 18th centuries Roman Catholic missionaries worked their way northward from Mexico into New Mexico and beyond. In 1793 the Scottish explorer Alexander Mackenzie crossed the Canadian Rockies. The members of the Lewis and Clark Expedition first crossed the mountains in what are now Montana and Idaho in 1805. They brought back much scientific data. Their success encouraged the U.S. government to sponsor a number of other major expeditions into the mountains throughout the 19th century. Surveys by engineers eventually led to the construction of railroads that passed through the mountains.

Much of the early exploration of the Rockies was done by pioneers known as mountain men. The mountain men were trappers and traders who did their exploring while in search of fur-bearing animals. People seeking gold also scoured the mountains.

Environmental issues

Timber harvesting, grazing, oil exploration, mining, and other activities have led to serious environmental concerns in the Rockies. Logging operations have reduced plant cover in the mountains, causing soil to wash away. Mining operations have polluted streams with minerals. The many dams on the Columbia, Colorado, Missouri, and other rivers have changed the region's natural environment. In addition, land that once was home to wildlife has been turned into farmland and pasture for cattle and sheep.