Arena Football League was the third longest-running professional football league in North America. The AFL played a form of indoor American football played on a 66-by-28 yard field. The sport was invented in the early 1980s and patented by Jim Foster, a former executive of the United States Football League (USFL) and the NFL. From a high of 19 teams in 2007, the league contracted to a low of four teams in 2018.
