 After some individually arranged contests, using mostly the same roster, Chicago managed to put together a 10-man roster and joined the nation's top organized league, which was now allowing entry to professionals.This league, known as the National Association of Base Ball Players, had been primarily dominated by the Atlantics and until very recently before the admitting of the Red Stockings and the White Stockings, had consisted of mostly baseball clubs from the New York, Philadelphia and Washington, D.C. areas.Despite this East Coast dominance, Chicago won the NABBP championship that year, although the title was disputed by the opposing club, the New York Mutuals.