Boulder Dam

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Located in the Black Canyon of the Colorado River on the Arizona-Nevada state line, thirty-five miles southeast of Las Vegas, the Boulder Dam, known since 1947 as the Hoover Dam, stands as a monument to modern engineering. It is a concrete gravity arch dam that spans 1,244 feet across the canyon and rises to a height of 726 feet; its width ranges from 660 feet at the base to forty-five feet at the crest. By controlling unpredictable floods, providing water to drought-ridden areas, and generating electrical power, the dam transformed the West and encouraged settlement of the region.

On December 21, 1928, following extensive debate over water rights and fiscal concerns, President Calvin Coolidge signed the Boulder Canyon Project bill, providing over $165 million to construct the dam. The Bureau of Reclamation awarded the contract to Six Companies, Inc., on March 11, 1931, ensuring employment for five thousand workers at the depths of the Depression. The government built Boulder City, complete with a school, a hospital, a general store, and a mess hall that served four thousand meals a day, to provide housing for single men and families.

Work on the dam began in May 1931 with the excavation of two tunnels on each side of the canyon to divert the river during construction. Workers then drained the site, stripped canyon walls of loose rock to provide a smooth surface for abutment, and drilled the canyon floor for the dam to rest on solid bedrock. In June 1933 workers started pouring concrete blocks in a series of columns using bottomdrop buckets hoisted into position by a cableway that spanned the canyon. A U-shaped powerhouse, with two arms extending downstream on either side of the canyon and connected by an arm spanning the face of the dam, housed generators that produced over 700,000 kilowatts of electricity, rendering Boulder Dam the largest hydroelectric facility in the world until the Grand Coulee Dam in Washington exceeded that level in 1949. Twin sets of intake towers controlled the flow of water to the powerhouse and reservoir outlets.

On February 1, 1935, workers sealed the diversion tunnels and allowed water to rise behind the dam, creating Lake Mead reservoir, named for Elwood Mead, the former commissioner of the Bureau of Reclamation. President Franklin Roosevelt dedicated the dam on September 30, 1935, proclaiming it "a twentieth-century marvel" that transformed the Colorado River "into a great national possession." Congress renamed the structure Hoover Dam in 1947, ending a controversy that began in 1930 when supporters proposed naming the dam after President Herbert Hoover for his contribution to the project. However, as more Americans began blaming Hoover for the Depression, Roosevelt's Secretary of the Interior, Harold Ickes, rejected the proposal and named the project Boulder Dam in 1933. Once public opinion of Hoover softened, Congress restored his name to the project that he helped to initiate.

The Boulder Dam harnessed the power of the Colorado River for the public good. It encouraged settlement and development of the West by thousands of farmers and businessmen who required a stable water supply, power generation, and protection from unpredictable floods. Combined with its contributions to municipal and recreational needs, Boulder Dam eventually benefited millions of Americans.



Dunar, Andrew J., and Dennis McBride. Building HooverDam: An Oral History of the Great Depression. 1993.

Kleinsorge, Paul L. Boulder Canyon Project: Historical andEconomic Aspects. 1941.

Records of the Bureau of Reclamation. Record Group No. 115: Project Histories, Boulder Canyon Project. National Archives and Records Administration. Rocky Mountain Region, Denver, Colo.

Simonds, William Joe. The Boulder Canyon Project:Hoover Dam. Available at:

Stevens, Joseph E. Hoover Dam, An American Adventure.1988.

United States Department of the Interior, Bureau of Reclamation. Boulder Canyon Project: Final Reports, Part IV—Design and Construction. 1941–1949.

Todd J. Pfannestiel

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Boulder Dam

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