Great Plains, extensive grassland region on the continental slope of central North America. They extend from the Canadian provinces of Alberta, Saskatchewan, and Manitoba south through W central United States into W Texas. In the United States the Plains include parts of North Dakota, South Dakota, Montana, Wyoming, Colorado, Nebraska, Kansas, Oklahoma, New Mexico, and Texas.

Physical Geography

The Great Plains slope gently eastward from the foothills of the Rocky Mts. at an elevation of 6,000 ft (1,829 m) to merge into the interior lowlands at an elevation of roughly 1,500 ft (457 m). The 1,500 ft (457 m) contour line, the 100th meridian of longitude, and the 20-in. (51-cm) isohyet of precipitation are arbitrarily used to mark the region's transitional eastern border. In places, however, it is clearly marked by an escarpment. Much of the Great Plains was once covered by a vast inland sea, and sediments deposited by the sea make up the nearly horizontal rock strata that underlie the area. Intrusive igneous rocks account for sections of higher elevation. The Great Plains region has generally level or rolling terrain; its subdivisions include Edwards Plateau, the Llano Estacado, the High Plains, the Sand Hills, the Badlands, and the Northern Plains.

The Black Hills and several outliers of the Rocky Mts. interrupt the region's undulating profile. The Saskatchewan, Missouri, Platte, Republican, Arkansas, Cimarron, and Canadian rivers flow in wide beds, generally from west to east, and are important sources of water. Rainfall decreases from east to west. Except for its easternmost margin and the elevations, the Great Plains have a semiarid climate, averaging less than 20 in. (51 cm) of precipitation annually. There are wide seasonal temperature ranges and winds of high velocity. In the westernmost sections the chinook, a warm winter wind, brings relief from bitterly cold and snowy winters. The dominant type of vegetation consists of shortgrass prairies; trees grow in moister areas and along water courses.

People and Economy

Although overall the Great Plains are sparsely populated, with much of the grassland devoted to farms and ranches, about half the people live in small to medium-sized urban areas; Edmonton, Alberta and Denver, Colo. are the largest cities in the region. Soils throughout the region are fertile and very productive when water is available. The principal crop is wheat, concentrated in the Spring Wheat Belt (generally N of Nebraska), where the colder climate delays sowing until spring, and the Winter Wheat Belt (centered in Kansas and Oklahoma), where the milder climate allows for winter sowing. Other crops include sorghum, flax, and cotton. Cattle and sheep are raised throughout most of the Great Plains. Oil, natural gas, coal, and gold are among its mineral deposits.

History

The Great Plains were long inhabited by Native Americans, who hunted the teeming herds of buffalo (see bison bison, large hoofed mammal, genus Bison, of the cattle family. Bison have short horns and humped, heavily mantled shoulders that slope downward to the hindquarters.
..... Click the link for more information. ) that roamed the grasslands and, due to wholesale slaughter by settlers and the U.S. army, were nearly extinct by the end of the 19th cent. The region was explored by the Spanish in the 17th cent. Until well into the 19th cent., the central Great Plains were called the Great American Desert. The first westward-bound pioneers bypassed the Great Plains. The railroads were largely responsible for their development after the Civil War. An initial wave of settlement was followed by emigration in times of drought. By the mid-1930s, decades of overgrazing and poor soil management in many of the Plains states had resulted in dust storms and the devastation of crops (see Dust Bowl Dust Bowl, the name given to areas of the U.S. prairie states that suffered ecological devastation in the 1930s and then to a lesser extent in the mid-1950s.
..... Click the link for more information. ).

Bibliography

See W. P. Webb, The Great Plains (1931, repr. 1981); N. R. Peirce, The Great Plains States of America (1973); B. W. Blouet and F. C. Luebke, ed., The Great Plains: Environment and Culture (1979).

Great Plains

Continental slope of central North America. It stretches from the Rio Grande at the U.S.-Mexico border in the south to the Mackenzie River delta along the Arctic Ocean in the north and from the Interior Lowlands and the Canadian Shield in the east to the Rocky Mountains in the west. The plains embrace parts of 10 U.S. states and 4 Canadian provinces, covering an area of about 1,125,000 sq mi (2,900,000 sq km). A high plateau of semiarid grassland, these prairie regions in both the U.S. and Canada produce the major proportion of wheat grown in each country and are also important cattle- and sheep-herding areas. Parts of the plains have reserves of coal and lignite, petroleum, and natural gas.