The National Football League (NFL) began in 1920 with predominately small towns and medium-sized cities as their core. Every season clubs would fold or move and then more teams would take their place. Most franchises failed to break even each year; even the large city teams such as the Chicago Bears and New York Giants. Part of the reason was that most folks followed professional baseball and little else. And if they did go to a football game, it was of the college variety.
So for years, the pro football world floundered and tried to stay afloat.