Dam of its scale had ever been attempted; on completion, it was the largest masonry dam in the world. The Hoover Dam is a massive concrete arch-gravity dam, constructed in the Black Canyon of the Colorado River, on the border between the US states of Arizona and Nevada between 1931 and 1936 during the Great Depression. In 1928, Congress authorized the project to build a dam that would control floods, provide irrigation water and produce hydroelectric power. The winning bid to build the dam was submitted by a consortium called Six Companies, Inc. Such a large concrete structure had never been
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