The Conventional Belief:
- The 1958 NFL Championship Game – the epic battle, decided in overtime, between the New York Giants and Baltimore Colts – “launched pro football into the stratosphere” of popularity. 
- The game, popularly referred to as “The Great Game Ever Played” (or “The Best Game Ever”) – featuring stars like Unitas, Huff, Ameche, and Barry  – “marked the beginning of the NFL’s popularity surge.” 
If the conventional belief is correct, then immediately following the 1958 Championship Game football should have been more popular than it was in earlier years.
It wasn’t. The few pieces of hard data we have does not fit the conventional story.
Since the 1930s, the Gallup polling organization has asked the American public which sport they prefer most. In this poll they do not distinguish between professional and college football. Still the data shows that “football” – however defined – was marginally less popular in December of 1960 (a full two years after the 1958 NFL Championship Game) than it was in March of 1937 (the earliest data-point available on the Gallup web-site). 
The story of the NFL’s growth in the 1960s is easy to tell without any mythologizing of the 1958 NFL Championship Game. As the 1960s progressed, pro football’s popularity grew rapidly. The American Football League was formed in 1960 to challenge the NFL. The AFL franchises brought pro football to new cities, and their television contract was more comprehensive than the existing NFL contract with CBS. The NFL quickly followed with a national TV deal with CBS that involved televising every NFL game of the season.
The attractiveness of football to the networks was obvious – football was popular enough to televise (though still a distant second to baseball), and quite cheap to broadcast, at least at first (the 1961 NFL/CBS deal to broadcast all NFL games cost CBS less than $5 million).
Football’s spike in popularity – especially as televised entertainment – can be charted by the increasing value of the NFL/CBS broadcast contracts through that decade: $5 million in 1961, $14 million in 1964 and nearly $19 million in 1966. During the course of the 1961-1964 CBS deal, CBS estimates that their NFL ratings grew by 50%. 
In 1967, of course, the AFL and NFL merged and stopped competing for players and TV contracts. In 1972, the Gallup poll found that football had surpassed baseball as America’s favorite sport.
 Ibid., “For the most part they regarded the fact that it had been remembered as the greatest game as just kind of a sportswriter’s gimmick. They knew that this was what Tex Maule had called the game, and sportswriters had referred to it as that. And over the years they have been asked probably about that game more than any other game they played.”
 Football Reigns as America’s Favorite Sport, January 30th, 2004. Gallup.com
 The Columbia Guide to America in the 1960s, David R. Farber, Beth L. Bailey. Page 318.