To put it very simply: American football evolved from a version of rugby played by a collection of elite colleges between the 1870s and the 1900s.

The question is more complex than it appears because there are two problems we have to solve: 1) when did football diverge from rugby and (2) when did it become recognisably the game we call American Football?

If we go back to 1870, we find the main colleges playing football according to the rules of soccer. Harvard had its own game with more emphasis on running and after playing McGill University it embraced rugby instead, Harvard and Yale competed under “concessionary rules” which were largely rugby in 1875 and 1876.

Remember that codified football was relatively new: in England the Football Association (soccer) had been formed in 1863 and the Rugby Football Union in 1871. What was going on in America was not so much following Britain as happening in parallel. Elite schools were codifying popular games to control and use them. The idea of playing ball games goes back centuries but the late nineteenth century saw them used for education, muscular Christianity and a definition of masculinity.

In 1876 Harvard, Princeton, Columbia and Yale drew up the Intercollegiate Football Association. This was still very similar to rugby: a running game with massed scrummages, but a series of modifications made it more recognisable to us. By 1882 the snap to the QB was in place and a clear division of possession with three downs to gain five yards was instituted and the sides were reduced to eleven each (rugby union has 15). It was still a running game with no forward pass or blocking. I think most historians agree that this was the period when the game diverged decisively from rugby. In 1888 blocking in front of the ball carrier was legalised. There was a lot of trial and error in how the rules evolved and a key figure was Walter Camp of Yale who dominated the development of the early game. His Yale teams lost only 14 times between 1876 and 1909 and while he was not a modern coach he instituted the tradition that the head of the football programme was an absolute dictator.

Some of the changes came about because of controversy. The sight of the best and brightest young men knocking lumps out of each other attracted both criticism and crowds. Kicking, throttling and butting were banned as were mass formations like the ‘flying wedge’ where blockers effectively carried the ball carrier like a battering ram.

In the 1890s the game spread to the Midwest and West Coast, making it genuinely national. Unfortunately, the game was become literally stuck in the mud with grinding line play dominating over broken field running. In 1906 a Joint Rules Committee which included Camp brought in reforms: Three downs to make ten yards (which Camp copied from Canada), a neutral zone at the line of scrimmage, clearer rules on unnecessary roughness,six men had to be on the line of scrimmage. Most radically they legalised the forward pass though only in a limited form.

In my opinion this is the point where something we can recognise as American Football was developed.

Works used: Michael Oriard, Reading Football John Sayles Watterson, College Football, History, Spectacle, Controversy