The modern history of American football can be considered to have begun after the 1932 NFL Playoff game, which was the first American football game to feature hash marks, the legalization of the forward pass anywhere behind the line of scrimmage, the first indoor game since 1902, and the movement of the goal posts back to goal line. Other innovations to occur immediately after 1932, were the introduction of the AP Poll in 1934, the tapering of the ends of the football in 1934, the awarding of the first Heisman Trophy in 1935, the first NFL draft in 1936 and the first televised game in 1939. Another important event was the American football game at the 1932 Summer Olympics, which combined with a similar demonstration game at 1933 World's Fair, led to the first College All-Star Game in 1934, which in turn was an important factor in the growth of professional football in the United States. American football's explosion in popularity during the second half of the 20th century can be traced to the 1958 NFL Championship Game, a contest that has been dubbed the "Greatest Game Ever Played". A rival league to the NFL, the American Football League (AFL), began play in 1960; the pressure it put on the senior league led to a merger between the two leagues and the creation of the Super Bowl, which has become the most watched television event in the United States on an annual basis.