50 Fun Facts About Hoover Dam

Hoover Dam was built in which gorge of the Colorado River?

Black Canyon is the gorge where the dam rose; engineers chose it over the canyon first surveyed upstream for its narrower walls and sounder bedrock, though the project kept the earlier canyon's name.

The dam straddles the border between Nevada and which other state?

Arizona is on the dam's eastern side; the state line crosses the crest, and the intake towers carry one clock showing Nevada time and another showing Arizona time.

The dam is roughly 30 miles southeast of which major city?

Las Vegas lies about 30 miles northwest of the dam; the city lobbied to be construction headquarters and even shut its speakeasies during the Interior Secretary's visit, but a purpose-built town got the job.

Which president formally dedicated the dam on September 30, 1935?

Franklin D. Roosevelt dedicated the dam on September 30, 1935, declaring 'I came, I saw, and I was conquered' in a speech broadcast nationwide by radio.

Under what official name was the dam dedicated in 1935?

Boulder Dam was the name the Interior Department adopted in 1933 and used at the 1935 dedication; the three-cent commemorative stamp issued for the ceremony reads 'Boulder Dam'.

How tall is the dam from foundation rock to the roadway on its crest?

The dam stands 726 feet from foundation rock to the roadway on its crest, which made it the tallest dam in the world when it was completed in 1936.

What structural type of dam is Hoover?

Concrete arch-gravity describes Hoover: 660 feet thick at the base and 45 feet at the crest, its curved upstream face carries the water's thrust into the canyon walls while its sheer mass resists overturning.

What is the rated generating capacity of the Hoover Dam power plant?

2,080 MW is the rated capacity of the Hoover power plant, whose generators sit in a U-shaped powerhouse at the dam's base and supply customers in three states.

In the 2007 film Transformers, what does the dam secretly house?

Megatron's frozen body is hidden inside the dam by the secret agency Sector Seven, which also keeps the AllSpark there; the Decepticons converge on the dam to thaw their leader.

In which 2015 disaster film does a massive earthquake collapse the dam?

San Andreas (2015) stages its first big set piece at the dam, where Paul Giamatti's seismologist watches a quake tear it apart; the 1978 Superman had already burst it on screen.

Which highway ran across the dam's crest before the bypass bridge opened?

U.S. Route 93 ran across the dam's crest for decades; after the 2001 attacks, truck traffic was restricted, and the highway moved onto the bypass bridge when it opened in 2010.

Which town was built specifically to house the dam's construction workers?

Boulder City was built by the federal government in 1931 to house dam workers under strict rules; it banned gambling from the start and kept the ban long after the dam was done.

Lake Mead holds which US record?

Largest reservoir by volume in the United States is Lake Mead's distinction: at full pool it stretches about 112 miles, reaches roughly 530 feet deep and stores roughly 28 million acre-feet.

Which consortium won the contract to build the dam in 1931?

Six Companies, Inc., a consortium that included Bechtel, Kaiser, Utah Construction and Morrison-Knudsen, won with a bid of $48,890,955, within $24,000 of the government's confidential estimate.

Who was the general construction superintendent who ran the job for the contractor?

Frank Crowe, the contractor's general superintendent, had spent his career building Reclamation dams and pioneered overhead cableways for delivering concrete; he later ran construction of Shasta Dam in California.

What were the workers called who dangled from ropes to blast loose rock off the canyon walls?

High scalers hung from ropes to drill and blast loose rock from the canyon walls, a risky, well-paid job that drew sightseers to watch their swinging acrobatics.

Which piece of safety gear did workers improvise at the dam by dipping cloth caps in tar?

Hard hats at the dam began as cloth caps dipped in tar and hardened, nicknamed 'hard-boiled hats'; after the homemade versions saved men from falling rock, the contractor ordered thousands of manufactured ones.

Had the dam been poured as one continuous mass, how long did engineers calculate the concrete would take to cool?

125 years was the estimated cooling time for a single monolithic pour, so the dam was built as interlocking blocks threaded with pipes carrying chilled water from an on-site refrigeration plant.

How much 1-inch steel cooling pipe was embedded in the concrete?

More than 582 miles of 1-inch steel pipe was laid through the blocks, fed first with river water and then with refrigerated water from a plant able to make 1,000 tons of ice a day.

According to the Bureau of Reclamation, how many workers are buried inside the dam's concrete?

None of the workers is entombed in the dam: each bucket raised a block's level by only about an inch, and crews of 'puddlers' worked every pour, so a body could not have gone unnoticed.

What is the Bureau of Reclamation's official count of construction fatalities?

96 is the Bureau's official industrial fatality count; broader tallies reach 112 by adding deaths away from the site, such as a 1922 surveying drowning during early river studies.

Which Interior Secretary ordered in 1933 that the dam stop carrying Hoover's name?

Harold L. Ickes, the New Deal Interior Secretary, struck Hoover's name from the dam in 1933, a partisan slap at the outgoing Republican president, and pointedly avoided the name at the 1935 dedication.

In what year did Congress unanimously restore the name Hoover Dam?

1947 is when Congress unanimously voted to restore the Hoover Dam name, and President Truman signed the resolution that April, ending a fourteen-year naming feud.

Which president signed the 1928 act that authorized the dam?

Calvin Coolidge signed the Boulder Canyon Project Act on December 21, 1928; it authorized $165 million for the dam and for the All-American Canal serving California's Imperial Valley.

Which architect gave the dam its streamlined Art Deco look after the first plans were called too plain?

Gordon B. Kaufmann, a Los Angeles architect, streamlined the dam's look after the Bureau's first plans, with a Gothic-inspired balustrade and eagle statues, were judged unworthy of so grand a structure.

What are the two 30-foot bronze statues at the dedication plaza called?

Winged Figures of the Republic are the two 30-foot bronzes flanking the flagpole; each was cast in one continuous pour and slid into place on blocks of ice to protect the polished metal.

What does the terrazzo star map at the base of the plaza's flagpole monument record?

The sky at the moment of the dam's dedication is what the star map fixes, laid out so precisely that astronomers far in the future could work out the exact date even if written records were lost.

Where did the four-lane Hoover Dam Bypass bridge, opened in October 2010, cross the river?

About 1,500 feet downstream of the dam, the bridge carries the highway roughly 900 feet above the river; through traffic across the crest ended when it opened, though the dam itself stayed open to visitor traffic.

The bypass bridge is co-named for which NFL player killed in Afghanistan in 2004?

Pat Tillman gave up an NFL safety's career with the Cardinals to enlist after 9/11 and died in Afghanistan in 2004; the bridge's other namesake, Mike O'Callaghan, was Nevada's governor from 1971 to 1979.

Lake Mead is named for Elwood Mead, who held what job?

Reclamation commissioner was Elwood Mead's post from 1924 until his death in January 1936, spanning the planning and construction of the dam; the reservoir was named for him that year.

What causes the white 'bathtub ring' visible around Lake Mead when the water is low?

Mineral deposits on once-submerged rock, mainly calcium carbonate left behind by the lake water, form the white band; the ring widens in drought years, when the surface drops well below the high-water line.

Why do the clock faces on the two intake towers agree for more than half the year?

Arizona skips daylight saving, so from March to November its Mountain Standard Time matches Nevada's Pacific Daylight Time and the two tower clocks agree; they differ only in winter.

Before he was president, Hoover chaired the 1922 negotiations that produced which water agreement?

The Colorado River Compact, signed on November 24, 1922, divided the river's flow between the Upper and Lower Basin states; Hoover, then Secretary of Commerce, chaired the commission that negotiated it.

Which honor did the dam receive in 1985?

National Historic Landmark status came in 1985; the dam had already been listed on the National Register of Historic Places in 1981 and named a National Historic Civil Engineering Landmark in 1984.

How many main turbine-generators does the powerplant have?

17 main turbine-generators sit in the powerhouse, nine in one wing and eight in the other; the plan was 16 large units, but two smaller ones took the place of one big unit.

On what date was the first concrete poured into the dam?

June 6, 1933 saw the first concrete placed, 18 months ahead of schedule, once the river had been diverted and the foundations cleared; the last bucket went in on May 29, 1935.

What was the maximum daily workforce recorded on the dam?

About 21,000 men worked on the project overall, with an average of 3,500 on any given day.

What was the nickname of the squatters' camp on the riverbank where families waited for dam jobs?

Ragtown was the nickname of the riverside squatters' camp, officially Williamsville, where families waited for dam jobs; during the brutal summer of 1931 its heat killed more than a dozen people.

Which company built the first Francis turbine-generators that went online at the dam in 1936?

Allis-Chalmers built the Francis turbine-generators that first went online in October 1936; more units followed over the years, and the final generator was not placed in service until 1961.

How many times did the spillway tunnels carry water in the dam's first fifty years?

Twice is the count: a 1941 test run and the 1983 floods; both times inspectors afterwards found cavitation damage in the tunnel linings that had to be repaired.

What did the Bureau of Reclamation secretly spend nine years doing after Lake Mead began to leak?

Completing a supplemental grout curtain took the Bureau nine years after the lake began filling; the original grouting had been rushed to stay ahead of the concrete pour, leaving gaps through which water seeped around the dam.

Which submerged Nevada town, drowned by Lake Mead in 1938, has resurfaced as the water level fell?

St. Thomas, a Mormon-founded farming town on the Muddy River, was abandoned as Lake Mead rose and went under in 1938; its foundations have reappeared whenever the lake dropped far enough.

Which sculptor created the dam's dedication plaza, its bas-reliefs and its memorial plaque?

Oskar J. W. Hansen, a Norwegian-born sculptor, designed the dedication plaza, the bas-reliefs on the elevator towers and the memorial plaque honoring the workers who died, along with the two towering bronzes beside the flagpole.

Which Interior Secretary first named it Hoover Dam at the 1930 railway ceremony?

Ray Wilbur, Hoover's Interior Secretary, announced the name at the September 1930 ceremony launching the construction railroad, citing a tradition of naming dams for presidents, though none had been so honored while in office.

Which Denver artist designed the Native American-inspired floor and wall motifs inside the dam?

Allen Tupper True, a Denver muralist, drew on Native American basket and pottery patterns for the terrazzo floors and wall motifs; he also devised a color scheme for pipes and machinery that the Bureau later adopted widely.

Whose fall from an intake tower in 1935 closed the fatality list, exactly 13 years after his father died at the site?

Patrick Tierney fell from an intake tower on December 20, 1935; his father, surveyor J. G. Tierney, had drowned at the site on December 20, 1922, while scouting dam locations, the first name on the list.

Which lower Colorado dam suffered concrete deterioration from alkali-silica reaction that Hoover avoided?

Parker Dam, built downstream in the late 1930s, developed damage from alkali-silica reaction in its concrete; Hoover escaped it, and core samples taken in 1995 showed its concrete had kept gaining strength six decades on.

How many diversion tunnels were driven through the canyon walls to move the river aside?

Four diversion tunnels, two in each canyon wall, were driven to carry the river around the site; each was 56 feet across, and together they ran more than three miles.

When the dam was handed to the federal government in March 1936, how far ahead of schedule was it?

More than two years ahead of schedule, the contractor turned the finished dam over to the government on March 1, 1936, despite brutal summer heat and construction methods never tried at that scale.

How much concrete went into the dam itself before pouring stopped in May 1935?

3,250,000 cubic yards of concrete went into the dam proper, with another 1,110,000 cubic yards in the power plant and associated works, enough to pave a two-lane highway from San Francisco to New York.