I watched the PBS documentary on Las Vegas tonight. They had Vegas getting its start in 1931 with the dam builders from Boulder City. In 1930, Boulder City did not exist. The census for that year has just a handful of miners living in Nelson township.
Although the TV show didn't mention it, Las Vegas really started with Stewart Ranch. Archibald Stewart's widow Helen sold it to wealthy railroader William Clark in 1902 and Clark auctioned off lots in 1905.