From 1906 to 1911, forward passes crossing the goal line on the fly or a bounce resulted in a turnover. Looking to encourage forward passing, the 1912 rule-makers removed that restriction but had to make another change. Until 1912, football fields did not have end zones. The area behind the goal line, called "in touch," did not have a deep boundary, but the rule makers wanted to limit how far behind the goal line passes could be legally caught, so they added the end line ten yards behind the goal line and defined the area between the goal and end lines as the “end zone."
Adding 10-yard end zones to the existing 110-yard field meant the field would be too long to fit in some stadiums, so they eliminated the center or 55-yard line, reducing the field of play by 10 yards. The new field fit in most stadiums, though it was tight quarters in a few.
As football increasingly embraced the forward pass over the decade or two, it became clear that the passing game became constrained as teams approached the goal line due to defenses having less space to cover. This is an obvious point to us in 2024, but it was a new realization in the 1920s, so it became an issue for those wanting more scoring in football.
Still, the passing game remained restricted in several ways at the end of the 1920s. Passes had to be thrown from at least five yards behind the line of scrimmage, eliminating the possibility of a quick passing game, and teams were penalized five yards for the second incompletion in a series of downs. In addition, incomplete passes in the end zone resulted in a touchback or turnover.
The restrictions resulted in offenses often choosing not to throw into the end zone. Also, football did not have hash marks until 1933, so teams down deep tended to run it up the middle to ensure they could kick a field goal on a future down. All these factors meant red zone scoring was far more difficult than today.
The 1920s also saw coaches around the country tossing out rule change ideas after each season and before the rule-making process began, leading Marquette coach Frank Murray to suggest in 1930 that the end zones should be 20 yards deep. Murray reasoned that the extra space would give receivers a better chance to get open and, by loosening up the defenders, make it easier to score on runs. His idea was questioned, in part, because the 20-yard end zones attached to 100-yard fields might not fit in some stadiums. Another question concerned where to locate the goal posts. Should they stay on the end line, further reducing scoring, return to the goal line, or find a spot somewhere in between?