History/FAQ

Frequently Asked Questions about Hoover Dam

Where is Hoover Dam Located?

In Black Canyon spanning the Colorado River between Arizona and Nevada, about 30 miles southeast of Las Vegas, Nevada.

When was work begun on Hoover Dam?

June 6, 1933

When was it completed?

May 29, 1935

How many men were employed during the dam's construction?

A total of 21,000 men worked on the dam with an average of 3,500 and a maximum of 5,218 daily, which occurred in June 1934. The average monthly payroll was $500,000.

What construction work was necessary before operations started at the dam site?

1. Construction of Boulder City, Nevada to house both government and contractor employees;
2. construction of seven miles of 22-foot-wide, asphalt-surfaced highway from Boulder City to the dam site;
3. construction of 22.7 miles of standard-gauge railroad from the Union Pacific main line in Las Vegas to Boulder City and an additional 10 miles from Boulder City to the dam site; and construction of a 222-mile-long power transmission line from San Bernardino, California, to the dam site to supply energy for construction

How tall is Hoover Dam?

It is 726.4 feet from foundation rock to the roadway on the crest of the dam. The towers and ornaments on the parapet rise 40 feet above the crest.

How much does Hoover Dam weigh?

More than 6,600,000 tons.

What type of dam is Hoover?

A concrete arch-gravity type, in which the water load is carried by both gravity action and horizontal arch action.

What is the maximum water pressure at the base of the dam?

45,000 pounds per square foot.

How much electricity does the dam produce?

When operating at full capacity the dam's 17 hydro-electric generators produce enough electricity to meet the needs of 750,000 people, or a city the size of El Paso, Texas

How much concrete is in the dam?

There are 4,360,000 cubic yards of concrete in the dam, powerplant and appurtenant works. This much concrete would build a monument 100 feet square and 2-1/2 miles high; would rise higher than the 1,250-foot-tall Empire State Building; or would pave a standard highway 16 feet wide, from San Francisco to New York City.

What was an unusual feature of Hoover Dam's construction?

The dam was built in vertical columns of blocks that varied in size from about 60 feet square at the upstream face of the dam to about 25 feet square at the downstream face. An estimated 215 blocks make up the dam. Adjacent columns were locked together by a system of vertical keys on the radial joints and horizontal keys on the circumferential joints (think "giant Lego set"). Concrete placement in any one block was limited to five feet in 72 hours. After the concrete was cooled, a cement and water mixture called grout was forced into the spaces created between the columns by the contraction of the cooled concrete to form a monolithic (one-piece) structure.

What were the quantities of principal materials used in the dam?

The principal materials, all of which were purchased by the federal government, were:

• 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 or 840 miles;
• structural steel, 18,000,000 pounds;
• miscellaneous metal work 5,300,000 pounds.

FUN FACTS ABOUT HOOVER DAM!

1. Hoover Dam is 726 ft. tall. That is 171 ft. taller than the Washington Monument in Washington D.C. and twice as tall as the Luxor Casino (338 ft.) in Las Vegas, Nevada.

2. At its base, Hoover Dam is as thick (660 ft.) as two footballs fields measured end-to-end.

3. As many as 20,000 vehicles a day drive across the 45 ft. wide top of the dam between Nevada and Arizona.

4. There is enough concrete in Hoover Dam (4 1/2 million cubic yards) to build a 2 lane road from Seattle, Washington to Miami, Florida or a 4 ft. wide sidewalk around the Earth at the Equator.

5. During peak electricity periods, enough water runs through the generators to fill 15 average sized swimming pools (20,000 gallons each) in 1 second.

6. Each of the 30 ft. wide penstocks (water pipes) can carry enough water to fill 900 bath tubs (100 gallons each) in 1 second, or 960,000 (12 oz.) cans of drink in 1 second.

7. Hoover Dam is shaped like a huge curved axe head, 45 ft. wide at the top and 660 ft. thick at the bottom.

8. Lake Mead is the largest reservoir in the USA and contains enough water to flood the entire state of New York with 1 ft. of water (26 million acre ft.).

9. If you drink water from the tap at Disneyland, Anaheim or Sea World in San Diego -- that water is coming from the Colorado River and Lake Mead, 300 miles away.

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

11. When operating at full power, the 17 generators can supply all the electricity needed by a city of 750,000 people.

12. Each generator weights (4 million pounds) as much as 4 1/2 fully loaded Boeing 747-400's.

13. The Colorado River is more than 1,400 miles long and supplies water to Los Angeles, San Diego, and Phoenix. Las Vegas gets almost all its water from Lake Mead. Lake Mead was made by Hoover Dam when it blocked the Colorado River and flooded the Mojave Desert.

14. Between 1931 and 1936 when the dam was built, 96 men were killed in industrial accidents. None were buried in the concrete.

15. The mascot dog and favorite pet of all the construction workers during the building of the dam was buried at Hoover Dam. The grave is near the Hoover Dam Tour Center and can be visited.

16. It would take $2,000,000 worth of copper pennies to make the copper buses (4 inch in diameter hollow square wires) that carry electricity inside the powerhouse.

17. Every state in the USA furnished supplies and materials for the construction of the dam.

18. More than 8.5 million pounds of dynamite was used to blast the foundation for the dam and 8 miles of tunnels through the canyon walls.

19. There are 2700 miles of transmission lines sending electricity from Hoover Dam to Los Angeles.