The Reclamation Act of 1902 created what is now called the Bureau of Reclamation, whose engineers sought water development projects on western federal lands. The Colorado River was selected because of its flooding and the enormous amount of water it could provide to surrounding states, and the Boulder Canyon Project Act of 1928 authorized construction of the dam. Because the river required a structure larger than any they had designed before, Bureau of Reclamation engineers undertook a massive project, while architect Gordon B. Kaufmann designed Art Deco elements including the intake towers, towers atop the dam, the Arizona and Nevada powerhouse exteriors, and an exhibit building. Six Companies, Inc. crews blasted diversion tunnels for the river, endured carbon-monoxide-choked conditions, worked with jackhammers from heights of 700 feet, and suffered casualties from falling equipment, rocks, and workers. Building the dam required thousands of laborers, with at least 21,000 workers needed during construction, and Boulder City was built about six miles away to house them. Though the work was immense and treacherous, the project was completed in 1935, just over four years after it began; the dam was designated a National Historic Landmark in 1985, and the highway across its crest provided an easy route between Las Vegas, Nevada, and Kingman, Arizona.