ALONG WITH BURGERS, brats, and BBQ, fireworks are a Fourth of July staple in the US. And they always have been. Founding father John Adams wanted “illuminations from one end of this continent to the other” to commemorate Independence Day even before the 13 colonies were fully independent. But the chemical cocktail that explodes in showers of color hasn’t changed all that much since those days. Sure, the shows have gotten far more sophisticated—technicians can now time brighter colors, comets, and complex displays to the crescendo of any song. Here’s what lights up the sky.