American Football League
Years of Existence: 1960-1970
The AFL was league upstart that seamlessly merged with the NFL. The league brought revered franchises (Patriots, Jets, Raiders, and Broncos to name a few) and legendary players (Joe Namath, Jim Nance, and George Blanda). Without the AFL, the NFL doesn't have the evangelical following that it does today, with a nation exponentially more concerned with replacement refs than an NHL season.