The Las Vegas Valley was discovered in the Mexican territory of Nevada in 1829 by a party seeking a new trade route from New Mexico to California. Mexico ceded the territory to the United States via the Treaty of Guadalupe Hidalgo in 1848, and in 1905 the city of Las Vegas was founded.

Two events spurred the city's growth: the construction of Hoover Dam, beginning in 1931, and the 1930 passage of Assembly Bill 98 by the Nevada legislature, which legalized gambling in the state. Several casinos opened in the 1940s, most notably Bugsy Siegel's Flamingo Hotel in 1946. Vegas became one of the most colorful cities in America, its politics dominated by cowboys and its economy run by the Mob, a home to eccentric billionaires, Mafia enforcers, Mormons, and showgirls. As the city continued to grow, the economy gradually passed into the hands of large corporations and somewhat more legitimate businessmen.