One of the underlying benefits of the Industrial Revolution was the leisure time it afforded the middle class. Prior to the Industrial Revolution, people who lived in agrarian societies did not have free time because they received no salary and there was always work to be done.
As factories allowed products to come to market in a quick, cheap, and efficient way, those products relied less on humans as artisans and more on machinery to handle the larger of work. These jobs granted salaries and disposable income. These jobs also created cities which began to take on distinct cultures. For example, during this time, Chicago became known for its expansive pork production. As people traveled to these cities and became ingratiated in the different cultures, they found sports like baseball and football to play an increasingly larger role in their cultural identity.
Baseball and football took advantage of ideas of power and masculinity, qualities which captivated ancient Romans. However, the various rules and strategies added an element of knowledge which provided a mental stimulus to patrons as well.
Marketing departments of different companies become involved in these sports, not only by making stadiums more impressive and engaging, but also by marketing professional players as cultural celebrities.
Increasing efficiency of media allowed fans to follow their teams easily, and reading box scores in newspapers became just as much a part of the mass culture as reading about the latest political developments.