PORTLAND, Ore. ( TheStreet) -- A professional sports franchise isn't a right, as money-hungry owners and cash-strapped cities are all too aware.Since 2000, six franchises from Major League Baseball, the National Basketball Association and the National Hockey League have pulled up stakes and switched towns. While baseball's Montreal Expos jumped to Washington in 2005 and the NHL's Atlanta Thrashers left for Winnipeg in 2011, the NBA has seen the Vancouver Grizzlies flee to Memphis in 2001, the Charlotte Hornets break for New Orleans in 2002, the Seattle Supersonics slip off to Oklahoma City in 2008 and the New Jersey Nets pay a few tolls on the way to Brooklyn in 2011. Meanwhile, for every town that has a faltering franchise, there's another with an empty or somewhat-empty building waiting to steal a pro team away. From Toronto trying on the NFL's Buffalo Bills once a season to Quebec building the NHL a giant safety net for one of its southern franchises, there's always a town looking for some more television time and potential revenue. Even Kansas City hasn't been picky about potential residents for its vacant Sprint Center, auditioning fumbling franchises from both the NHL and NBA for the position. What well-funded investors in Seattle made very clear during their pursuit of the Sacramento Kings earlier this year, meanwhile, is that fans in Salt Lake City, New Orleans, Milwaukee, Minneapolis, Phoenix and Portland, Ore., shouldn't take their professional teams for granted.