When American rugby transformed into Gridiron

How gridiron possibly came about.

When Teddy Roosevelt was playing rugby in the 1870s and NOT gridiron at Harvard the history books have a go that it was Teddy who forced the sports governing bodies to adopt new rules that ensured safer play at the turn of the century. But safer play from what? Rugby in its state was still played the world over by the turn of the century (thanks Britain!) – but what seemed to be happening in America was a perverse and more violent style of play with rules that broke from those in rugby elsewhere. Why and how did this come about?

For more info on the article, please visit the NY Times Upshot.