Second on the list of top ten largest casinos in the U.S. is the WinStar World Casino Resort in Thackerville, Oklahoma. That being the case, the largest casino in the U.S. The WinStar World Casino & Resort has more slot machines and casino floor space than any other casino in America. We’re only ranking these in terms of actual, casino floor space. Some resorts have large meeting rooms, arenas and shopping districts, however that space doesn’t count in the rankings. Here, we’re counting square footage devoted to gambling. In a country with over a thousand casinos, and tens of billions in annual gaming revenue, ten resorts stand tall as the biggest casinos in the United States.