This Depression-Era Marvel Controls the Colorado River and Powers Three States

Hoover Dam, Nevada

In 1935, workers finished what many thought was impossible: a 726-foot concrete dam that could power cities and control floods.

The Hoover Dam took five years to build and cost nearly 100 lives. It also created Lake Mead and brought electricity to millions of homes.

This is the story of America’s most famous dam.

The Colorado River Compact

Herbert Hoover played a key role in the dam’s creation years before construction started. As Commerce Secretary in 1922, Hoover chaired the Colorado River Commission.

This commission brought together representatives from seven states that relied on the Colorado River. Arizona, California, Colorado, Nevada, New Mexico, Utah, and Wyoming all competed for water rights.

Diverting the Mighty Colorado

Engineers faced their first major challenge before building the dam. They needed to divert the powerful Colorado River away from the construction site.

Workers dug four massive diversion tunnels through the canyon walls. Two tunnels ran through the Nevada side and two through the Arizona side.

Each tunnel measured 56 feet in diameter with the four tunnels stretching a combined length of nearly 16,000 feet, more than three miles total.

Men endured brutal conditions inside these tunnels. Temperatures reached 140 degrees while carbon monoxide and dust filled the air.

Working conditions grew so dangerous that workers staged a six-day strike in August 1931. Despite these challenges, crews completed the first tunnel in November 1932.

The Daredevil High Scalers

After diverting the river, workers had to prepare the canyon walls by removing loose rock. This job fell to men known as “high scalers,” who had to dangle from ropes as high as 800 feet up,

They used 44-pound jackhammers while dangling in midair. Many of them were former sailors, circus acrobats, and Native Americans who were at ease with heights.

These also workers created the first hard hats by coating cloth caps with tar.

The high scalers earned about 75 cents an hour, versus the 50 cents for regular dam workers.

Designing a Self-Cooling System

Engineers calculated that if poured as one massive structure, the concrete would take 125 years to cool and harden properly.

This slow cooling process would create tremendous heat, enough to bake 500,000 loaves of bread every day for three years.

To solve this problem, workers built the dam in vertical columns using interlocking blocks.

Engineers placed over 582 miles of cooling pipes inside, and cold water flowed through these pipes to draw heat away from the setting concrete.

A massive refrigeration plant operated at the construction site. This facility produced 1,000 tons of ice daily to cool the water flowing through the pipes.

Temperature sensors throughout the structure provided real-time data.

The Concrete Colossus

Hoover Dam required unprecedented amounts of concrete. The dam itself used 3.25 million cubic yards of the material.

Workers poured an additional 1.11 million cubic yards for the power plant and related structures.

The dam’s base measures 660 feet thick, the length of two football fields placed end to end.

An automated plant mixed the concrete on site. This hi-mix plant could produce 24 cubic yards of concrete every 3.5 minutes.

Engineers designed the dam as 215 interlocking concrete blocks. These blocks fit together like a giant three-dimensional puzzle.

Creating a New Town Just for the Dam

The federal government built Boulder City for the 5,000 workers and their families.

Unlike most American cities, Boulder City had no elected officials. A U.S. Bureau of Reclamation employee ran the entire town.

This manager had unusual authority. He could evict residents at will and set community rules.

Early Boulder City banned gambling and alcohol, a law that’s still in effect today.

The federal government kept control of Boulder City for nearly 30 years after dam construction ended. The city finally got self-rule in 1960.

The Human Cost of Construction

Official records show that 96 workers died during construction.

Reports indicate another 42 workers died from illnesses related to the project. Many historians believe carbon monoxide poisoning in the tunnels caused numerous undocumented deaths.

Workers faced extreme weather conditions. In June 1931, temperatures averaged 119°F, causing heat stroke and exhaustion.

The Naming Controversy

People initially called it Boulder Dam based on the Boulder Canyon Project Act.

In September 1930, Interior Secretary Ray Lyman Wilbur announced the structure would be named “Hoover Dam” after President Herbert Hoover.

When Franklin Roosevelt became president in 1933, his Interior Secretary Harold Ickes switched back to the Boulder Dam name. This decision reflected the political friction between the Democratic Roosevelt administration and former Republican President Hoover.

For years, Republicans generally said “Hoover Dam” while Democrats preferred “Boulder Dam.”

In 1947, Congress addressed the confusion. House Resolution 140 passed without a single opposing vote, officially restoring the name “Hoover Dam.”

President Harry Truman, a Democrat, signed legislation that permanently established Hoover Dam as the official name on April 30, 1947.

Powering the Southwest

Hoover Dam’s hydroelectric power plant transformed the Southwest. Its 17 generators produce enough electricity to power 1.3 million homes.

The first generator began operating in 1936, even before all construction finished. These initial units used Allis Chalmers-built Francis turbine-generators, advanced technology for the time.

By 1939, Hoover Dam stood as the largest hydroelectric facility in the world.

Today, the dam supplies electricity to public and private utilities across Nevada, Arizona, and California.

Lake Mead

Lake Mead, formed by Hoover Dam, is America’s largest reservoir by volume.

More than 25 million people depend on Lake Mead for drinking water, including communities across Nevada, Arizona, and California.

Visiting Hoover Dam

Hoover Dam is about 30 miles southeast of Las Vegas, Nevada, making it an easy day trip. You can join guided tours inside the dam’s structure, before spending time at Boulder City itself.

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