Definition: Crop farming on lands using an artificial supply of water rather than rainfall
Significance: Irrigated farming led to the profitable cultivation of acres that otherwise would not have been suitable for crop growing, the establishment of numerous subsidiary enterprises, and significant shifts in population.
Although most regions of the eastern United States receive sufficient rainfall for farming, lands west of the one-hundredth meridian, which runs from the Dakotas southward to Texas, are generally arid and need irrigation to be farmed. In areas where rainfall permits growth but is not abundant, irrigation can increase crop yields dramatically.
Early steps to encourage farming in the West met with limited success. During the 1870’s and 1880’s, a number of private irrigation companies were formed, but generally they were unable to deliver water to distant tracts and most failed within a few years. The Desert Land Act of 1877 allowed wouldbe farmers to buy land at a low price, provided part of the land came under irrigation within three years, a requirement often impossible to meet. The Carey Act of 1894 offered land to the states for irrigation projects, although few took advantage of it.
Far greater success came with the formation of the Bureau of Reclamation, created by the Newlands Reclamation Act of 1902. Under the bureau’s guidelines, the federal government financed and oversaw the damming of rivers, the creation of reservoirs, and the digging of canals, allowing water users to repay the costs gradually. Such projects, which initially employed large numbers of laborers, resulted in the cultivation of vast tracts of land and increased settlement in the western states. The spread of irrigated farming also encouraged the manufacture and marketing of farm equipment, fertilizers, and pesticides.
By the middle of the twentieth century, advances in technology made it possible to pump water from rivers and aquifers and deliver it to elevations beyond the reach of earlier systems. Irrigation systems featuring automated sprinkling also became widespread. Toward the end of the century, irrigated farming became increasingly common in the southeastern United States. The number of large, corporate farmsincreased significantly, while small, family farmsand farmjobs decreased. People also began to express concern about the long-term negative consequences of irrigation: salinization of soils, damage to riverine ecology by dams, and concentration of pollutants caused by irrigation runoff. In 2003, barely a century after the creation of the Bureau of Reclamation, nearly 53 million acres of the United States were under irrigation.

Further Reading
Pisani, Donald J.Water and American Government: The Reclamation Bureau, National Water Policy, and the West, 1902-1935. Berkeley: University of California Press, 2002.
Reisner, Marc. Cadillac Desert: The American West and Its DisappearingWater. Rev. ed.NewYork: Penguin, 1993.
Rowley, William D. The Bureau of Reclamation: Origins and Growth to 1945, Volume 1: Reclamation— ManagingWater in theWest. Denver, Colo.: Bureau of Reclamation, U.S. Department of the Interior, 2006.
See also: agribusiness; U.S. Department of Agriculture; Colorado River water; Dams and aqueducts; Farmlabor; Land laws; Rice industry; Water resources.