History of Arizona programs. Federal money started arriving with the Federal Emergency Relief Committee in 1930. Different agencies promoted aid to the unemployed, tuberculosis patients, transients, and illegal immigrants. The money ran out by 1931 or 1932, and conditions were bad until New Deal relief operations began on a large scale in 1933. Construction programs were important, especially Hoover Dam (originally called Boulder Dam), begun by President Herbert Hoover. It is a concrete arch-gravity dam in the Black Canyon of the Colorado River, on the border with Nevada. It was constructed by the Federal Bureau of Reclamation between 1931 and 1936. It operationalized
Geology of the Grand Canyon area deposits. At the same time, streams flowed from highlands in central Arizona north and across what is today the western Grand Canyon, possibly feeding a larger river. The mechanism by which the ancestral Lower Colorado River captured this drainage and the drainage from much of the rest of the Colorado Plateau is not known. Possible explanations include headward erosion or a broken natural dam of a lake or river. Whatever the cause, the Lower Colorado probably captured the landlocked Upper Colorado somewhere west of the Kaibab Uplift. The much larger drainage area and yet steeper stream gradient helped to further