Nevada legalized casino gambling. It was the Great Depression and Nevada’s tax revenues had cratered. Searching for new revenue sources, Nevada approved casinos.
In the 1920’s, the population in Los Angeles began rapid growth. It was also the decade when Hollywood began to draw the rich and famous to Southern California. Nevada leaders hoped to draw those customers to Las Vegas, which was situated as close to the Nevada-California border as possible.
Construction on the nearby Hoover Dam made a major city in the desert feasible for the first time. It would take a decade or so to happen, but the vision of a gambling destination in Las Vegas began in 1931.