is a concrete arch-gravity dam
in the Black Canyon
of the Colorado River
, on the border between the U.S. states of Nevada
. It was constructed between 1931 and 1936 during the Great Depression
and was dedicated on September 30, 1935, by President Franklin D. Roosevelt
. Its construction was the result of a massive effort involving thousands of workers, and cost over one hundred lives. Originally known as Boulder Dam
from 1933, it was officially renamed Hoover Dam for President Herbert Hoover
by a joint resolution of Congress in 1947.
Since about 1900, the Black Canyon and nearby Boulder Canyon
had been investigated for their potential to support a dam that would control floods, provide irrigation water and produce hydroelectric power
. In 1928, Congress authorized the project. The winning bid to build the dam was submitted by a consortium called Six Companies, Inc.
, which began construction of the dam in early 1931. Such a large concrete structure had never been built before, and some of the techniques were unproven. The torrid summer weather and lack of facilities near the site also presented difficulties. Nevertheless, Six Companies turned the dam over to the federal government on March 1, 1936, more than two years ahead of schedule. (Full article...