2010 FIFA World Cup

Soccer is the most popular youth sport in the United States. In 2002, 17.5 million American kids played in organized soccer leagues, not to mention the countless other children who gather for street scrimmages or spontaneous exhibition matches. Compare that to the classic pastime of Little League baseball, which had only 2.2 million participants in 2006.

But while soccer dominates the amateur market, most serious athletes in the U.S.