A colored postcard showing an artist's representation of The Babcock and Wilcox Pipe Plant next the construction site of Boulder Dam, a title that would later be changed to Hoover Dam. Because the penstock pipes at Hoover Dam were too large to be carried over railroads, this plant was built to fabricate the largest penstock pipes in the world. Transcribed onto the top border of the image: "The Babcock & Wilcox Pipe Plant, Boulder Dam."