There shouldn't be much of a surprise as to which NBA franchises have the most fans.
This map, via The New York Times' Tom Giratikanon, Josh Katz, David Leonhardt and Kevin Quealy, shows that a few of the league's greatest franchises have large fanbases. The data was based on Facebook likes, so although it isn't an exact science, it's a pretty good representation.
It looks like the Los Angeles Lakers are "America's team." Anyone who thinks this season may have some fans abandoning ship is sadly mistaken.
This map shows that the team still owns the city, seeing as how the Los Angeles Clippers aren't even shown. The research shows that the Lakers still have anywhere from three to eight times as many fans in Los Angeles compared to the Clippers.
One might notice that the Toronto Raptors aren't even shown. Here's what The Upshot—part of The New York Times—had to say on Canada: "Facebook data shows that the Raptors own Ontario, Canada’s most populous province, but haven't made many incursions into the United States. Though much of the rest of Canada looks Laker purple on our map, many of those areas are sparsely populated or have the Raptors as a close second."
If all of that wasn't enough, The Upshot (subscription required) broke down each current playoff matchup to show which teams the United States is rooting for to advance.