How did American football evolve from English rugby and soccer?

American football evolved from a blend of English soccer and rugby through a series of rule changes at elite American universities.12

Early intercollegiate games in the 1860s and 1870s were primarily soccer-style matches. However, Harvard University favored the "Boston Game," a hybrid of soccer and rugby. After experiencing rugby during matches against McGill University in 1874, Harvard adopted the style, which soon gained popularity among other schools. By 1876, a new Intercollegiate Football Association was formed based on rugby rules.1

The transformation into the distinct "gridiron" game was driven largely by Walter Camp, known as the "Father of American Football". Camp introduced critical innovations, most notably replacing the rugby "scrummage" with a controlled scrimmage line and establishing the system of downs, which required teams to advance a specific distance or surrender possession. These changes, alongside the introduction of 11-man teams, the quarterback position, and a structured scoring system, fundamentally separated American football from its rugby origins.34