The Football
Millions of Americans tune in to watch football on Thanksgiving every year and it all started because the owner of the Detroit Lions wanted to promote the game in his baseball-obsessed city and convinced NBC to broadcast the game.
Ever since that first NFL broadcast in 1934, the Lions have played on every Thanksgiving except during WW2. The Dallas Cowboys joined in on this NFL tradition in the 60s and America has had its post-dinner plans figured out ever since.