<P> Kickball is also played recreationally by adults and children, especially at the elementary school level . Its rules are largely identical to baseball, except that no bat is used and instead a large rubber ball is rolled along the ground for the "batter" to kick . </P> <P> Roller derby is a contact sport played on roller skates that has had brief surges of popularity throughout the 20th and 21st centuries . Roller Derby was portrayed in the 2009 film Whip It . Since September 2009, there were 350 women's, men's, and junior leagues in the U.S.A. </P> <P> For the most part, unlike sports in Europe and other parts of the world, there is no system of promotion and relegation in American professional sports . Major sports leagues operate as associations of franchises . The same 30--32 teams play in the league each year unless they move to another city or the league chooses to expand with new franchises . </P> <P> All American sports leagues use the same type of schedule . After the regular season, the 10--16 teams with the best records enter a playoff tournament leading to a championship series or game . American sports, except for soccer, have no equivalent to the cup competitions that run concurrently with leagues in European sports . Even in the case of soccer, the cup competition, the Lamar Hunt U.S. Open Cup, draws considerably less attention than the regular season . Also, the only top - level U.S. professional teams that play teams from other organizations in meaningful games are those in MLS . Since the 2012 season, all U.S. - based MLS teams have automatically qualified for the U.S. Open Cup, in which they compete against teams from lower - level U.S. leagues . In addition, three or four U.S. - based MLS teams (depending on the results of the U.S. Open Cup) qualify to play clubs from countries outside the U.S. and Canada in the CONCACAF Champions League . NBA teams have played European teams in preseason exhibitions on a semi-regular basis, and recent MLS All - Star Games have pitted top players from the league against major European soccer teams, such as members of the Premier League . </P>

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