Barbeque all the way.
Typical Fourth of July Menu:
Hot Dogs(White Hots and Red Hots), Hamburgs, Sausage (Italian and Polish), Barbeque Chicken, Ribs, Potato Salad, Macaroni Salad, Egg Salad, Tossed Salad, lobster/clams/Fish is big in the northeast, there is just tons of stuff.
We cannot forget the most important ingredient though. The fourth is not the fourth without mass consumption of alcohol. Beer is the most likely choice for that category.