John Wesley Powell
Library of Congress

John Wesley Powell
May - August, 1869: Early History

Major John Wesley Powell makes the first recorded trip through the Grand Canyon and down the length of the Colorado River. The one-armed Civil War veteran followed this expedition with a second trip down the Colorado in 1871, when he conducted geological studies that greatly expanded understanding of the topography of the region.


Theodore Roosevelt
Library of Congress

Theodore Roosevelt
June 17, 1902

President Theodore Roosevelt signs the Reclamation Act. Reclamation Service engineers begin their long series of investigations and reports on control and possible uses of the Colorado River.


Workers use train tracks to cross the flooded plain.
Union Pacific Railroad

Workers use train tracks to cross the flooded plain.
March, 1905

Torrential rains begin and lead to the Colorado River breaking into the Imperial Valley, creating an inland sea across a hundred and fifty square miles. It was two years, at a cost of more than $3 million, before the river is contained within its original channel. Blaine Hamann, former Bureau of Reclamation employee, recalls, “The river was an enemy, and only in short periods of time could you look at it as a useful river. Most of the time it was something that would kill you or ruin your farm.”


May 18, 1920

Congress passes the Kinkaid Act authorizing the Secretary of the Interior to investigate problems of Imperial Valley.


Arthur P. Davis

Arthur P. Davis
February, 1922

Arthur P. Davis is the chief author of the Fall-Davis report entitled “Problems of Imperial Valley and Vicinity.” Prepared under the Kinkaid Act and submitted to Congress, the report recommended construction of a high dam on the Colorado River at or near Boulder Canyon. The report also suggested that the government could recoup the cost of construction by selling the electric power generated by the dam to the cities in rapidly expanding Southern California.


November 24, 1922

Representatives of the seven Colorado River Basin States sign the Colorado River Compact in Santa Fe, New Mexico. Later in the year, the first of the Swing-Johnson bills to authorize a high dam and canal is introduced in Congress.


Calvin Coolidge
Library of Congress

Calvin Coolidge
December 21, 1928

The Colorado River Board of California reports favorably on a feasibility study concerning the Boulder Canyon Dam Project. The Boulder Canyon Project Act, introduced by Senator Hiram Johnson and Representative Phil Swing, both of California, passes in the House and Senate, and is signed by President Calvin Coolidge.


Herbert Hoover
Herbert Hoover Presidential Library

Herbert Hoover
June, 1929

Herbert Hoover takes charge of negotiations as six of seven basin states approve the Colorado River Compact. The basin states include Arizona, California, Colorado, Nevada, New Mexico, Utah, and Wyoming. Arizona, unhappy with the proposed plan for water distribution, is the one state that held out against the Compact. The resulting agreement leads to passage of the Boulder Canyon Project Act.


The men of Six Companies
Bureau of Reclamation

The men of Six Companies
March 11, 1931

The Bureau of Reclamation opens bids for the construction of Boulder (Hoover) Dam and Power Plant. The contract is awarded to Six Companies, a construction and engineering firm made up of some of the West’s most successful builders and designers of dams, bridges, roads, and tunnels. The winning bid was $48,890,995.


November 14, 1932

The Colorado River is diverted around the dam site.


June 6, 1933

First concrete is poured at Hoover Dam site.


February 1, 1935

The Hoover Dam starts impounding water in Lake Mead.


May 29, 1935

The last concrete is poured at the dam site.


September 30, 1935

President Franklin D. Roosevelt attends and speaks at the dedication of Boulder (Hoover) Dam.


Hoover Dam completed

The Hoover Dam completed
March 4, 1947

Officially declaring that the dam at Boulder Canyon be named Hoover Dam for former President Herbert Hoover, House Resolution 140 is introduced to Congress. It will pass two days later and move on to be approved in the Senate.


April 30, 1947

President Harry S. Truman signs resolution officially declaring that the dam at Boulder Canyon be named Hoover Dam.


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