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 relatively more important than they were before. Steeper cliffs and further widening the Grand Canyon and its tributary canyon system occurred. An average of two debris flows per year reach the Colorado River from tributary canyons to form or expand rapids. This type of mass wasting is the main way the smaller and steeper side canyons transport sediment but it also plays a major role in excavating the larger canyons. In 1963 Glen Canyon Dam and other dams farther upstream started to regulate the flow of the Colorado River through Grand Canyon. Pre-dam but still historic flows of the Colorado