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.