 The city of Las Vegas had lobbied hard to be the headquarters for the dam construction , closing its many <unk> when the decision maker , Secretary of the Interior Ray Wilbur came to town . Instead , Wilbur announced in early 1930 that a model city was to be built in the desert near the dam site . This town became known as Boulder City , Nevada . Construction of a rail line joining Las Vegas and the dam site began in September 1930 . 
