 Complete the following phrase:  The modern era of American football can be considered to have begun after the 1932 NFL Playoff game, which was the first indoor championship-game since 1902 and the first American football game to feature hash marks, forward passes anywhere behind the line of scrimmage, and the movement of the goalposts back to the 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 Worlds 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 footballs explosion in popularity during the second half of the 20th century can be traced to the 