Bureau director Arthur Powell Davis in 1922 outlined a plan before
Congress for a multipurpose dam in Black Canyon, located on the Arizona-Nevada
border. Named the Boulder Canyon project, after the original proposed
site, the dam would not only control flooding and irrigation, it would
generate and sell hydroelectric power to recoup its costs. Still, the
proposed $165 price tag concerned some lawmakers, while representatives
of six of the seven states in the river drainage area—Colorado, Wyoming, Utah, New Mexico, Arizona and Nevada —worried that the water would primarily go to California.
Secretary of Commerce Herbert Hoover
brokered the 1922 Colorado River Compact to divide the
water
proportionally among the seven states, but the legal wrangling continued
until outgoing President Calvin Coolidge
authorized the Boulder Canyon Project in December 1928. In honor of the
new president’s contributions, Secretary of the Interior Ray L. Wilbur
announced the structure would be called Hoover Dam at a 1930 dedication
ceremony, though the name didn’t become official until 1947.
As the Great Depression unfolded, hopeful laborers descended on Las Vegas
and set up camp in the surrounding desert for the chance to work on the
project. Those who were hired eventually moved to Boulder City, a
community specifically built six miles from the work site to house its
employees. Meanwhile, the U.S. government set about finding a contractor
to build the proposed 60-story arch dam. The contract was awarded in
March 1931 to Six Companies, a group of construction firms that had
pooled its resources to meet the steep $5 million performance bond.
The first difficult step of construction involved blasting the canyon
walls to create four diversion
tunnels for the water. Facing strict
time deadlines, workers toiled in 140-degree tunnels choked with carbon
monoxide and dust, conditions that prompted a six-day strike in August
1931. When two of the tunnels were complete, the excavated rock was used
to form a temporary coffer dam that successfully rechanneled the
river’s path in November 1932.
The second step of involved the clearing of the walls that would
contain the dam. Suspended from heights of up to 800 feet above the
canyon floor, high scalers wielded 44-pound jackhammers and metal poles
to knock loose material, a treacherous task that resulted in casualties
from falling workers, equipment and rocks.
Meanwhile, the dried riverbed allowed for construction to begin on
the powerplant, four intake towers and the dam itself. Cement was mixed
onsite and hoisted across the canyon on one of five 20-ton cableways, a
fresh bucket capable of reaching the crews below every 78 seconds.
Offsetting the heat generated by cooling concrete, nearly 600 miles of
pipe loops were embedded to circulate water through the poured blocks,
with workers continually spraying the concrete to keep it moist.
As the dam rose, block by block, from the canyon floor, the visual
renderings of architect Gordon Kaufmann took form. Electing to emphasize
the imposing mass of the structure, Kaufmann kept the smooth, curved
face free of adornment. The powerplant was given a futuristic touch with
horizontal aluminum fins for windows, while its interior was designed
to pay homage to Native American cultures.
With the body of water that would become Lake Mead already beginning
to swell behind the dam, the final block of concrete was poured and
topped off at 726 feet above the canyon floor in 1935. On September 30, a
crowd of 20,000 people watched President Franklin Roosevelt commemorate
the magnificent structure’s completion. Approximately 5 million barrels
of cement and 45 million pounds of reinforcement steel had gone into
what was then the tallest dam in the world, its 6.6 million tons of
concrete enough to pave a road from San Francisco to New York City. Altogether, some 21,000 workers contributed to its construction.
Hoover Dam fulfilled the goal of disseminating the one-wild Colorado
River through the parched Southwest landscape, fueling the development
of such major cities as Los Angeles, Las Vegas and Phoenix. Capable of
irrigating 2 million acres, its 17 turbines generate enough electricity
to power 1.3 million homes. The dam was designated a National Historic
Landmark in 1985 and one of America’s Seven Modern Civil Engineering
Wonders in 1994. It receives some 7 million visitors annually, while
Lake Mead, the world’s largest reservoir, hosts another 10 million as a
popular recreation area.