The anthem unites us. We're all Americans. Well, mostly, there's probably a few illegal aliens--sorry, undocumented migrants--at the game, but still, almost all Americans. So we stand united before dividing up into teams and trying to pummel each other senseless.
White, black, brown, yellow, red, or purple, democrat or republican, male or female, young or old, rich or poor, we're all Americans. Okay, all except for that guy right there.
It has always been a unifying pre-game event. Not working so well right now, huh?