Football originated in the United States in the second half of the 19th century as a cross between soccer and rugby. In 1873, four colleges met in New York City and established the Intercollegiate Football Association, which set out to establish the first official rules for intercollegiate football.
In 1869, Princeton University and Rutgers University competed in what is considered the first formal college football game. Following the game, these two schools, along with Yale University and Columbia University, created the IFA. Among the initial rule adoptions, the schools agreed upon setting the number of players on each squad at 15. These rule changes would not stay long, as Yale's head coach, Walter Camp, lobbied successfully to reduce the number of players on each team to 11. By 1902, with Camp's leadership the IFA had also established that a team had three downs or chances to gain 10 yards or they would be forced to give up the football to the opposing team. Finally, in 1912, the fourth down was added, and the game took on a much more recognizable look to football of the modern period.
In 1892, the Pittsburgh Athletic Club competed against the Allegheny Athletic Association. William (Pudge) Heffelfinger, who played for the Allegheny squad, was paid $500. Due to the transaction, the game is considered to be the first professional football game in history.