Every year the Battle of Germantown, October 4, 1777, is reenacted (on the closest convenient Saturday) in Philadelphia. Speeches made, movements described, muskets and a random cannon fired, and when the choking smoke clears, grilled sausages and donuts, with beer or lemonade. The Cliveden estate hosts Revolutionary soldiers and t-shirted tourists, lounging on the grass under the trees, like a time portal has been left open and things are leaking.
In recent years, there has been a move to reconsider how accurate to make this, given that there are actual guns and real shootings in Philadelphia, and some of the neighbors have started to find this a bit traumatizing. Or perhaps they always did, but they were tired of being dismissed as party poopers.
When and how Americans began the practice of battle reenactment is unclear; it pre-dates renaissance fairs, which might have actually been inspired by a cross between reenactments, nomadic Grateful Dead tour followers, and hobbits, but that's another story.