All of the professional sports teams?

Relocation of professional sports teams is a practice which involves a sporting franchise moving from one metropolitan area to another, although occasionally moves between municipalities in the same conurbation are also included. Professional teams in North America are generally privately owned and operate according to the wishes of an owner, making this practice much more common there than in other areas of the world where sporting teams are clubs owned by local members. Unlike most professional sport systems worldwide, sports organizations in North America generally lack a system of promotion and relegation in which poorly performing teams are replaced with teams that do well in lower-level leagues.

North America lacks comprehensive governing bodies whose authority extends from the amateur to the highest levels of a given sport. Unlike in other countries, where one may invest in a local lower-level club and through performance see that club rise to major league status, the only three ways a North American city can host a major league sports team are through league expansion, forming/joining a rival league or, most commonly, relocation. A city wishing to get a team in a major professional sports league can wait for the league to expand and award new franchises.

However, as of 2013 each of the major leagues has 30 or 32 franchises. Many current owners believe this is the optimal size for a major league, and with the possible exception of the NFL's desire to return to Los Angeles, North America's second largest market, none of the major leagues are believed to be imminently considering expansion, and in fact Major League Baseball actually considered contraction in 2002 to be effective for the 2007 season (of the Montreal Expos and Minnesota Twins), until the sport's players union sued Major League baseball to prevent the dissolution of the teams. In the end, nothing happened to the Twins, who had the issue of their contraction, a new stadium, resolved with the opening of Target Field in 2010, and the Expos relocated to Washington, D.C. to become the Washington Nationals.

In past decades, aspiring owners whose overtures had been rejected by the established leagues would respond by forming a rival league in hopes that the existing major league will eventually agree to a merger, the new league will attain major league status in its own right and/or the established league is compelled to expand.