I enjoyed @SITimLayden's essay on football's outsized importance. But since he asked: no, that idea didn't start in the 1940s. It began in the late 19th century, and there's some great scholarship explaining how it became an entrenched part of US culture. A partial reading list: 
Michael Oriard's writing played a big part in my decision to do sports history, so I gotta list him first amazon.com/Reading-Footba…
Oriard is especially good at explaining the multiple and contested cultural meanings that football held for Americans. Hist first book looked at football's early years, this one (my fav from him) looks at the 1920s-1950s amazon.com/King-Football-…
Julie Des Jardin's biography of Walter Camp is fantastic. She uses Camp as a lens to explain the ways in which football became associated with American manhood amazon.com/Walter-Camp-Fo…
This one by S.W. Pope is not exclusively about football, but it shows the ways sports (including football) were linked with American nationalism & military preparedness (esp. during WW1) amazon.com/Patriotic-Game…
Ronald Smith's book about the rise of big-time college sports is a classic in the field. Like Pope's book, it's not exclusively about football, but football plays a major role in his analysis amazon.com/Sports-Freedom…
If you want to read only one book that focuses specifically on how football became associated with the educational mission of American universities--and then became too big to separate, despite glaring problems--Brian Ingrassia's is the one to read amazon.com/Rise-Gridiron-…
I don't usually like to describe books as "magesterial," but when it comes to the history of college football, John Watterson's book is as close to that mark as they come. Its scope extends far beyond the late 19th/early 20th century, too amazon.com/College-Footba…
There are a couple excellent case studies that critically examine the rise of big-time college football through the lens of specific programs. Murray Sperber's 600+ page look at Notre Dame is fascinating amazon.com/Shake-Down-Thu…
And so is Robin Lester's account of the rise and fall of University of Chicago football--an original member of the conference that became the Big Ten, and one of the few schools to voluntarily step away from big-time football amazon.com/Staggs-Univers…
Moving beyond origins of football's outsized importance, Brad Austin's recent book shows how college football withstood criticism in the 1930s and even expanded its importance in American life (Austin, it should be noted, does not focus only on football) amazon.com/Democratic-Spo…
It's impossible to understand football's meaning in US culture without taking race into account. While many of the books listed above don't ignore race, Charles Martin's book brings black athletes (and the racist structures they faced) to the forefront amazon.com/Benching-Jim-C…
Finally, Matthew Lindaman's brand new intellectual biography of John L Griffith--Big Ten commissioner from the 1920s into the 1940s--zeroes in on Griffith's role in promoting and defending football as a character-building institution of national importance amazon.com/Fit-America-Ad…
I'll stop there for now. All those books explain and examine football's cultural importance before the 1940s. There are a whole bunch of other books that explore how football maintained and expanded its place in American life after the 1940s.
Just realized I didn't link to the excellent @SITimLayden essay that inspired this thread in the first place. If you've made it this far, check it out now: si.com/nfl/2018/08/23…
I know I said I was finished, but this book definitely deserves a spot in the thread:
And while we're at it, keep this forthcoming book on your radar. It takes on a super important and vastly understudied topic in football history
