How the Mob Built Las Vegas

Las Vegas did not exist as a significant settlement until the railroad arrived in 1905, and the city as it is known today was largely built on gambling revenue legalized in 1931. The Flamingo Hotel, which opened in 1946 and is often cited as the first major resort on what became the Las Vegas Strip, was financed and built by organized crime figures led by Benjamin Bugsy Siegel. The hotel opened $6 million over budget, and Siegel was murdered in his girlfriend's Beverly Hills living room six months later. The mob presence in Las Vegas casino ownership continued until the 1980s when corporate ownership gradually took over.

Source: Wikipedia