Colorado River too much of the lower basin allotment; in 1944 a compromise was reached in which Arizona would get a firm allocation of , but only if California's allocation was prioritized during drought years. These and nine other decisions, compacts, federal acts and agreements made between 1922 and 1973 form what is now known as the Law of the River. On September 30, 1935, the United States Bureau of Reclamation (USBR) completed Hoover Dam in the Black Canyon of the Colorado River. Behind the dam rose Lake Mead, the largest artificial lake in the U.S., capable of holding more than two
Steamboats of the Colorado River Colorado route, and was the model for all the steamboats on the river thereafter. From 1859, prospectors dispersed up the Colorado River valley in the next few years, finding gold deposits along the river as far as the Black Canyon. In 1860, gold was found across the Colorado River from Potholes in Arizona, in placers at La Laguna. The strikes that followed in the next four years would make George A. Johnson and his two partners wealthy. By March 1861, the secession crisis had led to the closing of the Butterfield Overland Mail. February 19, 1861, the Bascom Affair led