Leagues have historically avoided Las Vegas for two main reasons. Until recently, it wasn’t a particularly large metro area by population. Now, however, it ranks 30th — and is bigger than 12 areas (including Salt Lake City, Raleigh, and Buffalo) that do have pro teams.
The other factor, though, has been the simple fact that Nevada law allows gambling on sports.
The worry is that the proximity of gambling would lead to match fixing, in which people with a stake in the outcome pay players to lose on purpose — like in 1919, when eight players on the Chicago White Sox were allegedly paid to lose the World Series. This episode led Major League Baseball to take the strongest stance against gambling of all the major sports: Pete Rose, for instance, was banned from baseball for life for betting on games while he was the manager of the Cincinnati Reds.
—Joseph Stromberg writing for Vox about Las Vegas and the coming “gamblification” of American pro sports. After years without a pro sports team, Las Vegas is building a new arena and rumors suggest that the NHL may expand there.