Some strictly-American definitions of a major league exclude the NHL, which, although it holds a dominant role in Canadian society, has struggled to gain wide support in American markets outside hockey's regional strongholds of the Northeast and Upper Midwest; this list, though, includes NHL teams, as the league's revenues, player salaries and media coverage are still significantly closer to those of the NBA than those of any of the other U.S. and Canadian team sports' top-level professional leagues.
Some strictly-Canadian definitions include the Canadian Football League. The CFL's support and media coverage compare to that of the "Big Four" within Canada, and since 1997, the CFL and NFL have shared a cooperative agreement that recognizes the CFL's role within its home country. Of CFL cities, only Toronto hosts more than one other major league club; four others host NHL teams, while 3 other cities as of 2007 don't have teams in the Big Four.
The CFL and MLS are indisputably the fifth and sixth most popular leagues on the continent (in which order is debatable). Therefore, this list includes a ranking by teams in the Big Four, and a separate ranking also including teams in the CFL and MLS (the Big Six).
Though teams are listed here by metropolitan area, the distribution and support of teams within an area can reveal regional fractures below that level, whether by neighborhood, rival cities within a media market or separate markets entirely. Baseball teams provide illustrations for several of these models. In New York City, the Yankees are popularly dubbed the "Bronx Bombers" for their home borough and generally command the loyalties of fans from the Bronx, parts of Brooklyn, Staten Island, and Manhattan, while the Mets play in Queens and draw support from Queens, Brooklyn and parts of Long Island, revealing a split by neighborhood. The San Francisco Giants and Oakland Athletics represent rival cities within the Bay Area, a single media market. Though the Washington Nationals and Baltimore Orioles share a metro area, their cities anchor separate media markets and hold distinctly separate cultural identities.