ABSTRACT
The importance of irrigation in the United States is illustrated by this statistic: while irrigated land is but one-seventh of all cropland, it provides more than one-fourth of total crop value. By enabling cultivation of desert soils and boosting crop yields per acre elsewhere, irrigation has become a crucial factor in the nation's agricultural output. The amount of land under irrigation has tripled since 1940, and while regional shifts have occurred, the total acreage is still increasing. 1
