American football evolved in the United States, originating from the sports of association football and rugby football. The first game of American football was played on November 6, 1869, between two college teams, Rutgers and Princeton, under rules based on the association football rules of the time. During the latter half of the 1870s, colleges playing association

football switched to the Rugby Union code, which allowed carrying the ball. A set of rule changes drawn up from 1880 onward by Walter Camp, the “Father of American Football”, established the snap, eleven-player teams, and the concept of downs; later rule changes legalized the forward pass, created the neutral zone, and specified the size and shape of the football.