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Hoover Dam

Herbert Hoover

Hoover Dam: Herbert Hoover was the 31st American President who served in office from March 4, 1929 to March 4, 1933. One of the important events during his presidency was the Hoover Dam.

Definition and Summary of the Hoover Dam
Summary and definition:
The Hoover Dam is a concrete, arch-gravity dam and its purpose is to provide hydroelectric power, water storage, irrigation and flood control. It is located in Black Canyon on the Colorado River, in Nevada, 35 miles from Las Vegas. In 1994, the American Society of Civil Engineers named the Hoover Dam as one of America's Seven Modern Civil Engineering Wonders.

The Hoover Dam was built during the Great Depression. Construction work began on April 20, 1931 and the dam was completed on March 11, 1936. The design themes, colors and patterns on the exterior of the dam reflect the Art Deco style and are inspired by original motifs used by the Navajo and Pueblo Native American tribes. The awe-inspiring Hoover Dam and Lake Mead attract over 10 million visitors a year. The Lake Mead National Recreation Area is one of the most popular U.S. national parks.

Where is the Hoover Dam ? The Hoover Dam is located within the Black Canyon on the Colorado River, in Nevada, 35 miles from Las Vegas.

When was the Hoover Dam built? The Hoover Dam was built during the Great Depression. Construction work began in 1931 and it was completed in 1936. The exact start date was April 20, 1931 and the completion date was March 11, 1936

Why is the Hoover Dam important? The Hoover Dam is important because of the many benefits it provided:

  • Irrigation, dependable water supplies and water storage

  • Colorado River Flood Control

  • The production of Hydroelectric Power

  • The improvement of navigation along the Colorado River

  • A by-product of the Hoover Dam was the creation of many recreational facilities and its role as a tourist attraction

Facts about Hoover Dam
The following fact sheet contains interesting facts and information on Hoover Dam.

The Boulder Canyon Project Act was approved on December 21, 1928. It was described as an Act to provide for the construction of works for the protection and development of the Colorado River Basin and other purposes

U.S. Congress agreed to fund the project on July 7, 1930. This was in the midst of the Great Depression when 25% of Americans were unemployed.

The contract to construct the dam was awarded to a consortium of Six Companies, Inc.,

The planned location was at Boulder Canyon. However, geologists then determined that Black Canyon, about 8 miles downstream, was a more suitable place to build the dam.

Work began on the 'Hoover Dam' in 1931 under the instruction of President Herbert Hoover and then handed over to Hoover's successor, Franklin D. Roosevelt, in 1936. President Hoover was blamed for many of the disastrous effects of the Great Depression and the feat of engineering was immediately referred to as the 'Boulder Dam'. It was not until 1947, long after the animosity had ended that it was renamed the Hoover Dam.

What type of dam is is it? The Hoover Dam is a concrete arch-gravity type, in which the water load is carried by both gravity action and horizontal arch action.

Over 21,000 unemployed men found work building the Hoover Dam together with the construction of a town, called Boulder City, to house 15,000 workers.

Many of the unemployed, poverty stricken and homeless construction men brought their wives and children with them to the Hoover Dam construction site. Houses had not yet built and, like so many others during the Great Recession, they were forced to live in tents or makeshift lean-tos. Their camp was nicknamed 'Rag Town'. There was no sanitation and their shelters were inadequate for the extreme weather conditions.

Hoover Dam Deaths: The construction work on the Hoover Dam took its toll and 96 men were killed in on-site industrial accidents. Others died from the heat or carbon monoxide poisoning incurred whilst working. As many as 100 other people, including wives and children, of the workers, died from heat, polluted water or disease.

Hoover Dam was the most expensive engineering project in U.S. history at the time of its construction. The project was completed two years ahead of schedule and cost less than the original budget of  $49 million.

The construction of the Hoover Dam virtually ended the possibility of destructive floods striking the region. Prior to construction of the project communities along the lower Colorado River were often devastated by terrible floods. The unpredictable and rampant flows of the Colorado river made it difficult to maintain a sustainable and prosperous community.

Impact and Benefits: The Hoover Dam provided many benefits to the surrounding areas:

  • The Colorado River was controlled and regulated for the first time in history

  • Farmers in Nevada, Arizona, and California received a dependable supply of water and irrigation creating improved agricultural land

  • Irrigated lands supply large amounts of produce for America's markets

  • Water is supplied to than 16 million people in the arid desert of the southwest

  • It provided for flood control of the Colorado River

  • Cities such as Los Angeles, San Diego, and Phoenix were provided by the Hoover Dam with an inexpensive source of electricity which improved industrial development

The building of Hoover Dam blocked the Colorado River and flooded the Mojave Desert creating Lake Mead, the largest man-made reservoir in the United States of America. Lake Mead provides 550 miles of coastline and is 110 miles long with a depth of 500 feet. The by-product of the Hoover Dam the creation of a large site for outdoor recreation, and a massive boost to tourism in the area. Tourists and residents come to Lake Mead for boating, swimming, fishing, camping, picnicking, water skiing and hunting.

Before construction work could even start on the Hoover Dam, the Colorado river had to be diverted. This difficult a task was achieved by drilling four huge tunnels through the solid rock walls and cliff faces of the Black Canyon. The largest of these tunnels was 3 miles long and had a diameter of 50 feet.

More than 8.5 million pounds of dynamite was used to blast the foundation for the Hoover Dam and 8 miles of tunnels through the Black Canyon walls.

Digging the foundations was a major factor in ensuring the overall integrity of the Hoover Dam. The mud and muck at the river bottom had to be removed. Workers, with the help of power shovels, sometimes had to dig down over 40 feet (12 meters) below. They excavated over 382,300 cubic meters (500,000 cubic yards) of muck and mud in order to reach the bedrock

Workers called "high scalers" had the extremely dangerous task of blasting the walls to create a smooth joining surface for the Hoover Dam.

The Hoover Dam was built in vertical columns or blocks that varied in size from about 60 feet square at the upstream face to 25 feet square at the downstream face.

Stats and Facts about the Hoover Dam:

  • Height: 726.4 feet (221.3 meters)

  • Weight: Over 6,600,000 tons

  • Crest length: 1244 feet (379.2 meters)

  • Crest width: 45 feet (13.7 meters)

  • Base width: 660 feet (201.2 meters)

  • Volume of concrete: 4.25 million cubic yards (3.24 million cubic meters)

How much cement was required for the construction of the Hoover Dam? More than 5 million barrels of concrete. The daily demand for concrete during construction was from 7,500 to 10,800 barrels per day.

To prevent the concrete from overheating, then contracting and then crumbling, steel tubes were inserted and pumped with chilled water from a specially-built refrigeration plant. The pipes were later filled with grout and remain part of the structure of the Hoover Dam.

Stats and Facts about the Materials used in the construction of the Hoover Dam:

  • Reinforcement steel: 45,000,000 pounds

  • Gates and valves: 21,670,000 pounds

  • Plate steel and outlet pipes: 88,000,000 pounds

  • Pipe and fittings, 6,700,000 pounds (840 miles)

  • Structural steel: 18,000,000 pounds

  • Other metal work: 5,300,000 pounds.

The Colorado River is more than 1,400 miles long and supplies water to Los Angeles, Phoenix and San Diego. Las Vegas receives almost all its water from Lake Mead.

Lake Mead is located by Hoover Dam in Boulder City, Nevada. It is on the Colorado River about 24 mi from the Strip southeast of Las Vegas, Nevada

The lake was named after Elwood Mead (January 16, 1858 January 26, 1936), who was the commissioner of the U.S. Bureau of Reclamation from 1924 to 1936 during the Boulder Canyon Project

Stats and Facts about Lake Mead:

  • Shoreline: 550 miles (885 kilometers)

  • Surface Area: 162,916 acres

  • Length when full: 110 miles (177 kilometers)

  • Capacity: 27,620,000 acre-feet (34.1 billion cubic meters)

  • Maximum depth: 500 feet (152 meters)

Hoover Dam is one of the world's largest producers of hydroelectric power. The power generated by the powerplant helps to serve the need of people in California, Arizona and Nevada. The approximate percentage of power delivered to each state by the Hoover Damis as follows:

  • Nevada: 23.4 %

  • Arizona: 19 %

  • California: 57.6 %

Stats and Facts about the Hoover Dam Powerplant:

  • The U-shape powerplant structure is located at the base of the dam

  • Each powerplant wing is 299 feet (nearly 20 stories) above the powerplant foundation

  • There are 10 acres of floor space the powerplant galleries

  • Length (each wing): 650 feet (198 meters)

  • Width (each wing): 55 feet (16.8 meters)

  • Height (each wing): 75 feet (22.8 meters)

  • Commercial generating units: 17 main turbines

  • Each of the 17 generators can supply electricity to 100,000 households

  • Number of Station service units: 2 (to run dam and powerplant)

  • Nameplate capacity: 2080 megawatts (including station service)

  • Water reaches the turbines via four pressure penstocks  (water pipes) , two on each side of the river

  • Shutoff gates control water delivery to the units

  • Each of the 30 ft. wide penstocks can carry enough water in just 1 second to fill 900 bath tubs

The initial design of the Hoover Dam concentrated on the functionality of the dam rather than the aesthetics. The dam was therefore initially adorned with eagle statues with Gothic style inspired railings.

Architect Gordon B. Kaufmann was then appointed to redesign the exteriors. His aim was to create some elegant designs, in the Art Deco style, for the exterior of the dam. Gordon B. Kaufmann was responsible for streamlining the buildings and designing the sculptured turrets tand the clock faces on the towers which feature the time zones in Arizona and Nevada (Pacific and Mountain time zones).

Gordon B. Kaufmann then brought in architect Allen Tupper True to design the floors and the walls. Allen Tupper True based his designs on original motifs of the Navajo and Pueblo Native American tribes who had inhabited the region for so many years. The colors and the images were based on the characteristic landform of stepped mesas of the Southwestern landscape together with the Navajo and Pueblo representations of local wildlife, water, clouds, lightning and rain.

The design themes, colors and patterns used by Allen Tupper True and Gordon B. Kaufmann are continued throughout the walkways and the interior halls

American sculptor, Oskar J.W. Hansen, produced many of the sculptures at the Hoover Dam and the concrete bas-reliefs found on the elevator towers.  The bas-reliefs shows the multipurpose benefits of Hoover Dam: Flood control, Navigation, Irrigation, Water storage and Power.

The five bas-reliefs on the Nevada elevator tower shows the multipurpose benefits of Hoover Dam: Flood control, Navigation, Irrigation, Water storage and Power.

The five bas-reliefs on the Arizona elevator tower depict "the visages of those Indian tribes who have inhabited mountains and plains from ages distant."

The beautiful terrazzo floor featuring a star map, or celestial map, was also designed by Oskar J. W. Hansen. The unique star map, calculated by astronomers, shows the Northern Hemisphere sky preserving the accurate date of when President Franklin D. Roosevelt dedicated the Hoover Dam on September 30, 1935 for future generations.

Hansen's principal work is the monument of dedication on the Nevada side of the Hoover dam. A 142-foot flagpole rises from a black, polished base that is flanked by two winged figures. The statues, called the Winged Figures of the Republic, are 30 feet high. The Winged Figures of the Republic express "the immutable calm of intellectual resolution, and the enormous power of trained physical strength, equally enthroned in placid triumph of scientific accomplishment."

Another unique aspect of the design of the Hoover Dam is that all the pipes and machinery are color-coded.

The Memorial plaque on the plaza, dedicated to the 96 construction workers that lost their lives during the construction project, was designed by Oskar J.W. Hansen.

There is also another memorial to a Black Labrador called 'Mix'. The Labrador was the mascot dog and favorite pet of the construction workers. Mix was killed in an accident when he was 10 years old. His grave, which was jack hammered into the solid rock cliff, is on the Nevada side of the dam. A plaque above his grave has the following inscription, "On February 21, 1941, the life of this devoted animal came to an end when a truck under which he was sleeping rolled over him. The grave below was completed by workers later that same day."

Guided Tours: Guided Tours by Bureau of Reclamation guides are conducted daily (except Christmas and Thanksgiving Day). Opening hours are from 9:00 a.m. to 5:00 p.m. (Pacific Time)

  • The visitor center offers interactive multi-media exhibits and audiovisual presentations

  • An overlook on top of the visitor center provides an awe inspiring view of the Hoover Dam, Lake Mead and the Black Canyon

US American History
1929-1945: Depression & WW2

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