Black and white image of the construction phase of the Boulder Canyon Project, also known as Hoover Dam. This image features the first round of drilling to enlarge the upper portal of diversion tunnel No. 2. The welded steel "Jumbo Rig" mounted on the truck has 25 air drills on it. The swing shift crew standing next to the rig prepare for work. Note: Boulder Dam was officially renamed Hoover Dam in 1947.

Black and white image of the Young Presidents' Organization Convention Chairman, Dick Woodward (left), and Hoover Dam Project Manager, Frank Lord, greeting Bureau of Reclamation Commissioner, Ellis L. Armstrong, upon his arrival to a celebration held by the Young Presidents' Organization at the Hoover Dam powerhouse. The party for nearly 1,000 people was held on the roof. The visitors, all wearing hard hats, were the first to use this setting.

Black and white image of the Bureau of Reclamation Commissioner, Ellis L. Armstrong (right), greeting Art Linkletter (left) upon arrival to a party held by the Young Presidents' Organization. The party for nearly 1,000 people was held on the roof of the powerhouse at Hoover Dam. The visitors, all wearing hard hats, were the first to use this setting.

The view of cars parked along a street in front of a building containing multiple shops, including the Boulder Dam Service Bureau and the Theatre Candy Shop. Transcribed onto the large sign plastered across the top of the building: "Free Boulder Dam Motion Pictures. Visitors Welcome. Boulder Dam Service Bureau." Transcribed across the three smaller signs on the building, reading from left to right- First: "Boulder Dam Service Bureau. Souvenirs, Post Cards, Official Booklets, Rest Rooms." Second: "Double Feature - George O'Bien in "Wind Jammer," and Tex Ritter in "The Mystery of the Hooded Horsemen." " Third: "Theatre Candy Shop. Cold Drinks & Sandwiches."

Black and white image of an abandoned steam tractor. Description from Special Collections accompanying image: "According to the story told, this was one of the first three tractors ever built. One was shipped here to Eldorado Canyon to move ore and one was shipped to Death Valley for the Borax works (it is still in Death Valley). The other one was sent to South America to a mine. The one in Death Valley supposedly worked out fairly well being used mostly in sand. This one, it is told, was not too successful. The drive mechanism was by way of teeth on the inside of the big black wheels, driven by a pinion gear at the top. Small stones fell into the wheel and stuck in the grease necessitating frequent stops to remove the stones. The driver stood on a platform at the rear. May 1947."