Yes, the movie is infinitely enjoyable, but it does take liberties with Bugsy's life:
The film shows Siegel making his first trip to the West Coast during WWII. He made his first trip in 1933, and two years later had moved there more or less full time. He'd been to Vegas many times before the War, trying to get the sawdust joints in town to buy into the Transnational Racing Wire.

After the Harry Greenberg murder rap was dismissed, Bugsy thought it would be prudent to hole up in Vegas for a while. He found seven hotels operating, some with air conditioning, but all in the "Western corral" style. He tried to buy into El Rancho Vegas but was rebuffed. He did buy into the El Cortez, and got Lansky and some of his NY pals to invest. They doubled their money in less than a year. That's when he set his sights on the Flamingo. It was already called that by its owner, Billy Wilkerson, publisher of the Hollywood Reporter, whose degenerate gambling left him without the means to finish it. Bugsy bought him out, and convinced his Cortez investors to put in their profits (and a lot more) to finishing the Flamingo. As you said, PB, Bugsy didn't really "invent" Vegas, but he was the first to envision it as a modern, Monaco or Miami Beach west of the Mississippi.

BTW: Big Greenie didn't try to find refuge with Bugsy. And Bugsy didn't take him for a ride. Greenie tried to hide from Bugsy. Murder Inc. sent Allie Tick Tock Tannenbaum and Frankie Mr. Gray Carbo to Bugsy. The three hunted Greenie down. Carbo pulled the trigger; Bugsy drove the crash car.


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