The History of the Hoover Dam: When, Why, and How It Was Built

Few structures capture the scale of American engineering quite like Hoover Dam. Rising more than 700 feet above the Colorado River just outside Las Vegas, it has controlled floods, stored water, and generated electricity for the Southwest for nearly a century. Hoover Dam was built between 1931 and 1936, and it remains one of the most visited engineering landmarks in the country.

If you've ever wondered when Hoover Dam was built, why it was built, who built it, or how much it cost, this guide covers every detail and shows you the easiest way to see this engineering marvel for yourself on a Hoover Dam tour with Christianson Tours.

When Was Hoover Dam Built?

Hoover Dam was built between 1931 and 1936, during the height of the Great Depression. Construction began in April 1931, and the dam was completed and turned over to the federal government on March 1, 1936 more than two years ahead of its original schedule. It officially opened later that year, with President Franklin D. Roosevelt dedicating the dam on September 30, 1935, though final construction work continued into 1936.

Why Was Hoover Dam Built?

Hoover Dam was built to solve three urgent problems facing the American Southwest in the early 20th century:

Flood control : The Colorado River flooded unpredictably, threatening farms and communities in the Imperial Valley and beyond.
Water storage and irrigation: The region needed a reliable water supply to support agriculture and growing desert cities like Las Vegas, Phoenix, and Los Angeles.
Hydroelectric power : A dam on the Colorado River could generate low-cost electricity for homes, farms, and industry across Nevada, Arizona, and California.

The project, originally named the Boulder Canyon Project, was also a critical source of employment during the Great Depression. Tens of thousands of workers arrived in Nevada hoping for a job on the dam, and the project ultimately employed over 21,000 people across its five years of construction.

Who Built Hoover Dam?

No single construction company in the 1930s was large enough to take on a project of this size. Instead, six construction firms that consist of Utah Construction Company, Pacific Bridge Company, MacDonald & Kahn, J.F. Shea Company, Morrison-Knudsen, and the Six Companies founded by Warren Bechtel pooled their resources into a joint venture called Six Companies, Inc.

Six Companies won the federal contract in March 1931 with a bid of $48,890,955, narrowly beating out competing bidders. The project's chief engineer, Frank Crowe, had decades of experience building dams for the U.S. Bureau of Reclamation and is widely credited with the construction innovations that let the project finish years ahead of schedule.

How Was Hoover Dam Built?

Building a dam of this size in the middle of the Nevada desert required solving problems no construction crew had faced before. The process unfolded in several major stages:

Building Boulder City: Before major construction could begin, a dedicated town was built six miles from the site to house the thousands of workers and their families, since no infrastructure existed near the remote canyon.
Diverting the Colorado River: Crews blasted four diversion tunnels through the canyon walls, each large enough to reroute the entire river around the construction site.
Clearing the canyon walls: High scalers rappelled down the canyon on ropes to remove loose rock, one of the most dangerous jobs on the project.
Excavating to bedrock: With the river diverted, workers dug down through riverbed silt and debris to reach solid rock, creating a stable foundation for the dam.
Pouring the concrete: Because a single continuous pour would have taken over a century to cool, engineers poured the dam in interlocking column-shaped blocks, cooled by an internal network of pipes carrying refrigerated water. In total, the dam and its powerhouse used roughly 4.3 million cubic yards of concrete.
Installing the power plant: Once the dam was complete, massive generators and turbines were installed to convert the force of the released water into electricity, a system still in use today.

The dam was built as an arch-gravity design curved to push the force of the water into the canyon walls, while its own enormous weight helps hold it in place. At the time, it was the tallest dam and the largest concrete structure ever built.

How Much Did Hoover Dam Cost?

Hoover Dam cost approximately $49 million to build roughly $48.9 million based on the winning Six Companies bid. Adjusted for inflation, that figure is equivalent to somewhere between $850 million and $1.16 billion in today's dollars, depending on the index used. When the surrounding infrastructure, including the power plant and transmission systems, is factored in, total project costs are often cited closer to $165 million in 1930s dollars. Remarkably, Six Companies completed the project both ahead of schedule and under budget.

Why Hoover Dam Still Matters Today

Hoover Dam wasn't just a Depression-era engineering feat — it continues to shape life across the Southwest nearly a century later. Its benefits reach far beyond the Colorado River:

Water supply: The dam created Lake Mead, the largest reservoir in the United States by volume, which supplies water to roughly 25 million people across Nevada, Arizona, California, and northern Mexico.
Clean, reliable power: Hoover Dam's hydroelectric plant generates enough electricity to serve about 1.3 million people in Nevada, Arizona, and California, without burning any fossil fuel to do it.
Flood and drought protection: By regulating the Colorado River's flow, the dam prevents the destructive flooding that once threatened farms and towns downstream, while storing water for use during dry years.
Economic engine: Beyond power and water, Hoover Dam supports agriculture, industry, and a thriving tourism economy, drawing roughly 7 million visitors a year to the region.
Engineering legacy: The techniques pioneered at Hoover Dam, from block-and-cooling-pipe concrete pours to large-scale river diversion, became the blueprint for major infrastructure projects worldwide.

See Hoover Dam for Yourself with Christianson Tours

Reading about Hoover Dam is one thing , standing on top of it, looking down 700 feet at the Colorado River, is another entirely. Christianson Tours offers two easy ways to experience this engineering marvel from Las Vegas, with no rental car or planning required:

Hoover Dam Tour : A half-day express tour dedicated entirely to the dam, with roughly two hours of free time to explore the visitor center, walk the top of the dam, and take in photo opportunities from the bypass bridge.
Grand Canyon West Rim Tour : See Hoover Dam as part of a full-day adventure, with a 10–15 minute photo stop at the dam on your way to Eagle Point and Guano Point at the Grand Canyon's West Rim.

Every Christianson Tours trip includes hotel pickup near the Las Vegas Strip, comfortable coach buses, and knowledgeable guides who bring the history of Hoover Dam to life along the way. Book your Hoover Dam tour today and see nearly a century of American engineering up close.

Conclusion

Hoover Dam stands as one of the most remarkable engineering achievements in American history , built in five years during the depths of the Great Depression, by a consortium of six construction companies working under conditions no one had faced before. From diverting the Colorado River to pouring millions of cubic yards of concrete by hand-built systems, every stage of its construction pushed the limits of what was possible in the 1930s. Nearly a century later, it still generates power, stores water, and draws millions of visitors each year. The best way to appreciate that history is in person, and Christianson Tours makes it simple to see Hoover Dam on a comfortable, guided day trip from Las Vegas. with Christianson Tours today, and get ready to explore the wonders of Hoover Dam.

Book your tour with Christianson Tours today, and get ready to explore the wonders of Hoover Dam.

Frequently Asked Questions

When was Hoover Dam built?

Hoover Dam was built between 1931 and 1936. Construction began in April 1931 and the dam was completed on March 1, 1936, over two years ahead of schedule.

Why was Hoover Dam built?

Hoover Dam was built to control flooding on the Colorado River, provide a reliable water supply for irrigation and growing desert cities, and generate hydroelectric power for the Southwest. It also created thousands of jobs during the Great Depression.

Who built Hoover Dam?

Hoover Dam was built by Six Companies, Inc., a joint venture of six construction firms formed because no single company was large enough to take on the project alone. Frank Crowe served as the project's chief engineer.

How was Hoover Dam built?

Workers first diverted the Colorado River through four tunnels blasted into the canyon walls, then excavated down to bedrock and poured the dam in interlocking concrete columns cooled by internal piping, since a single solid pour would have taken decades to cure.

What year was Hoover Dam built?

Hoover Dam was constructed primarily in 1931 through 1936, with the dedication ceremony held in September 1935 and final completion in March 1936.

How much did Hoover Dam cost?

Hoover Dam cost approximately $49 million to build in the 1930s, which is roughly $850 million to over $1 billion in today's dollars depending on the inflation measure used.

Can I visit Hoover Dam from Las Vegas?

Yes. Hoover Dam is about a 45-minute drive from Las Vegas. Christianson Tours offers guided bus tours directly to the dam, including a dedicated Hoover Dam Tour and a Grand Canyon West Rim Tour that includes a Hoover Dam photo stop.