This aerial view shows a crest of the Hoover Dam, aka Boulder Dam, showing the highway leading across it on July 16, 1935. The road, soon to be opened to the public, will provide an easy route between Las Vegas, Nev., and Kingman, Arizona. The intake towers jut up on the other side of the dam in Boulder City, Nevada. (AP Photo)
Pres. Franklin Roosevelt viewed the Boulder Dam project for the first time in Nevada at its border with Arizona, Sept. 30, 1935. Walker Young, in charge of the work for the U.S. Bureau of Reclamation is shown at left pointing out points of interest to the president. The president’s military aide is at right. (AP Photo)
Pres. Franklin D. Roosevelt is shown on top of the Boulder Dam, nearly complete except for power units, just before he dedicated the huge structure on the Nevada side of the Nevada-Arizona border, Sept. 30, 1935. The dam, which is considered the world’s greatest engineering feat, left the president "speechless," he said. (AP Photo)
In this U.S. Bureau of Reclamation photo, construction gangs on the great Boulder Dam, who work night and day, have pushed the past the half-way mark, months ahead of schedule, shown . the foundations for power plants on the Nevada side be seen in the left foreground, and those on the Arizona side in the right foreground. The dark line running up and down the center of the dam is a crack through the entire dam, left temporarily to aid in the cooling of the concrete in an undated photo. The dam will be street high when finished. (AP Photo)
A three million pound gate of tunnel no. 4, shown above at left, was ready to close, Feb. 1, 1935, stopping flow of the Colorado River at the Boulder Dam, thus starting filling of a huge reservoir. The above photo taken just before the gate stated closing shows a coffer dam built across the entrance of tunnel no. 3, which has been diverting the river through the canyon walls and around the dam on the Arizona side. (AP Photo)
These few tent-houses, now sheltering 35 surveyors, are located on the site of the unnamed city which soon will grow large enough to house the thousands of men who will work on the Boulder Canyon dam, huge Colorado River flood control and hydro-electric project undertaken by the U.S. government, shown Sept. 13, 1930. The unnamed city is located near Las Vegas, Nevada on the brink of the Black Canyon. (AP Photo)
Secretary Ray Lyman Wilbur drives the last spike into the railroad leading from Las Vegas, Nevada to the site of the Hoover Dam – better known as the Boulder Dam, Sept. 19, 1930. The spike, made of silver, signalized actual beginning of construction on the $165,000,000 project. Left to right: Congressman William Eaton, of Colorado; Senator Key Pittman, Nevada; Secretary Wilbur, and left Senator Samuel Shortridge. (AP Photo)
The extent to which waters of the Colorado River have been backed up by Boulder Dam is shown, Sept. 30, 1935, as photographed from a Transcontinental & Western airplane, high over the dam, which is shown in the right foreground. An island appears in the center of the lake. (AP Photo)
Construction continues Jan. 9, 1932 as workers construct the retaining wall that gives support to the road leading over the top of Hoover Dam. Labor troubles were experienced during the huge engineering project on the Colorado River near Las Vegas, Nevada. (AP Photo)
More than 700 feet over the Colorado River bed, workers put the finishing touches on the Hoover Dam on Aug. 12, 1931. The dam was built by the Bureau of Reclamation, Department of the Interior. (AP Photo)
Huge crowds attended the ceremonies at Las Vegas, Nevada, Sept. 17, 1930. Starting actual work on the Hoover Dam. Secretary Ray Lyman Wilbur gave the principal address. Announcing the change of name from boulder dam to dam, in honor of the President. Secretary Wilbur Drove a silver spike into the last tie of the road connecting Las Vegas with the dam site. (AP Photo)
On the eve of the opening of the post office of Boulder City, the new town which is springing up in Nevada as work starts on the gigantic Hoover Dam of the Boulder Canyon Project, Reclamation Bureau officials called to extend best wishes to Postmaster J.L. Finney, April 15, 1931. Left to right, W.R. Armstrong, general superintendent of the United Pacific; R.F. Walter, chief engineer of the Reclamation Bureau; a carpenter for the Six Company Inc.; Postmaster Finney, Dr. Elwood Mead, Commissioner of Reclamation, and P.W. Dent, assistant to Dr. Mead. (AP Photo)
Construction of the Hoover Dam continues, a constant stream of large trucks dumping fifty tons of soil a minute, built an earth fill dam across the Colorado River, forcing its turbulent waters into two fifty-foot diversion tunnels on the Arizona canyon wall on Nov. 15, 1932. (AP Photo)
A steel bucket holding eight cubic yards dumps the first load of concrete for the foundation of the Hoover Dam on the floor of Black Canyon in Boulder City, Nev., June 9, 1933. The concrete form is three-sided as the fourth wall will be formed by the live rock of the Arizona reef for the dam. (AP Photo)
A view of the huge Boulder Dam operation from a high point on the Nevada rim of the Black Canyon, shown Sept. 11, 1934. The immensity of the project can be seen from this picture. (AP Photo)
A steel bucket holding eight cubic yards dumps the first load of concrete for the foundation of the Hoover Dam on the floor of Black Canyon in Boulder City, Nev., June 9, 1933. The concrete form is three-sided as the fourth wall will be formed by the live rock of the Arizona reef for the dam. (AP Photo)
This is a downstream view of the Hoover Dam showing the immense concrete blocks rising from the bedrock of Black Canyon’s floor, which will be the core of the dam, near Boulder City, Nev., Aug. 12, 1933. Concrete is being poured into the forms at the rate of about 6,000 cubic yards daily. (AP Photo)
This is a view of the Hoover Dam from upstream as construction continues near Boulder City, Nev., Feb. 1, 1935. The crack in the upper center of the dam is a space left open for cooling and settling of the concrete and will be filled as work progresses. (AP Photo)
This view shows the interior of one of the tunnels through which the Colorado River will be diverted around the Hoover Dam site in Boulder City, Nev., April 18, 1932. The project is in the early stages of construction. (AP Photo)
View of Boulder City, Nevada, April 1, 1932. Boulder City was built about eight miles from the site of Hoover Dam to house the employees working there. Thirty-five hundred men and their families live at the city and are transported to the dam site by bus. (AP Photo)
The tent and automobiles pictured are on the site selected for Boulder City, seven miles from the site of the proposed Boulder dam which will house the 2,500 workers on the huge dam project, shown March 16, 1932. Workmen will begin immediately to erect house and business structures in the city. Miss Antoinette Johnson braved the desert wastes for a peek at the site of the little cityin Nevada. (AP Photo)
This is an aerial view of the Hoover Dam of the Boulder Canyon project situated in Black Canyon on the Colorado River, on the border of the states of Nevada and Arizona, in Boulder City, Nev., March 13, 1936. A portion of the Mead Lake is shown behind the 731-foot high concrete structure. Water from the lake flows at the ratio of several thousand gallons per second from outlet valves on the Arizona side, below dam. Intake towers are behind the dam on each side. (AP Photo)
A crowd is assembled in the power house of the Hoover Dam in Boulder City, Nev., during ceremonies in which U.S. President Franklin Roosevelt pressed a button in Washington, D.C., starting the 3,500 horsepower generator in the foreground, creating the first power from the dam in Boulder City, Sept. 11, 1936. (AP Photo)
This is the 3500 horsepower generator in Boulder City on September 10. President Roosevelt started boulder dam by pressing a button in Washington. This was but a beginning, for within a month the giant 115,000 horsepower generators will start power from the $165,000,000 project to southern California, 300 miles away. Year not provided. (AP Photo)
Night view of Boulder Dam and Mead Lake taken from a plane United airlines-western air express shows the roadway over the dam top illuminated and the candles atop the intake towers casting their reflections on the water, Sept.22, 1936 in Boulder City, Nevada. (AP Photo)
Aerial view of Hoover (Boulder) Dam on the Colorado River, Dec. 11, 1948. (AP Photo)
On July 7, 1930, construction began on Boulder Dam, which is known today as Hoover Dam.
The dam was built during the Great Depression, drawing more than 5,000 workers to the cauldron of the Nevada desert.
Ninety-six construction workers died constructing the historic dam from 1931 to 1936, according to a report from the U.S. Bureau of Reclamation. More than 100 additional dam workers died off the job from causes including pneumonia, meningitis and typhoid fever.
However, no one is buried in Hoover Dam. The 3.25 million cubic yard dam, covering more than 220 acres, is made of small concrete squares of about 8 cubic feet, according to a 2015 Review-Journal article.
President Franklin D. Roosevelt officially dedicated the dam on Sept. 30, 1935.
In 1947, the 80th Congress passed legislation officially designating the Boulder Canyon Project’s key structure “Hoover Dam” in honor of President Herbert Hoover.
Hoover Dam is a National Historic Landmark and has been rated by the American Society of Civil Engineers as one of America’s Seven Modern Civil Engineering Wonders, the bureau reported.
In 2014, Darwin Colby, the last known Hoover Dam construction worker, died in his sleep at 98.
