<P> Violent thunderstorms occur east of the Rockies . Tornadoes occur every spring on the southern plains, with the most common and most destructive centered on Tornado Alley, which covers eastern portions of the West, (Texas to North Dakota), and all states in between and to the east . </P> <P> Agriculture varies depending on rainfall, irrigation, soil, elevation, and temperature extremes . The arid regions generally support only livestock grazing, chiefly beef cattle . The wheat belt extends from Texas through the Dakotas, producing most of the wheat and soybeans in the U.S. and exporting more to the rest of the world . Irrigation in the Southwest allows the growing of great quantities of fruits, nuts, and vegetables as well as grain, hay, and flowers . Texas is a major cattle and sheep raising area, as well as the nation's largest producer of cotton . Washington is famous for its apples, and Idaho for its potatoes . California and Arizona are major producers of citrus crops, although growing metropolitan sprawl is absorbing much of this land . </P> <P> Local and state government officials started to understand, after several surveys made during the latter part of the 19th century, that only action by the federal government could provide water resources needed to support the development of the West . Starting in 1902, Congress passed a series of acts authorizing the establishment of the United States Bureau of Reclamation to oversee water development projects in seventeen western states . </P> <P> During the first half of the 20th century, dams and irrigation projects provided water for rapid agricultural growth throughout the West and brought prosperity for several states, where agriculture had previously only been subsistence level . Following World War II, the West's cities experienced an economic and population boom . The population growth, mostly in the Southwest states of New Mexico, Utah, Colorado, Arizona, and Nevada, has strained water and power resources, with water diverted from agricultural uses to major population centers, such as the Las Vegas Valley and Los Angeles . </P>

What is the climate in the west region