The All-America Football Conference (AAFC) was a professional American football league that challenged the established National Football League (NFL) from 1946 to 1949. One of the NFL's most formidable challengers, the AAFC attracted many of the nation's best players, and introduced many lasting innovations to the game. However, the AAFC was ultimately unable to sustain itself in competition with the NFL. After its folding, three of its teams were admitted to the NFL: the San Francisco 49ers, the Cleveland Browns and the original Baltimore Colts (not to be confused with the later Baltimore Colts team, now the Indianapolis Colts).