Setting mildly explosive things on fire has been a part of the Fourth of July since before there was even an anniversary to celebrate. It was John Adams, writing to his wife in 1776, who suggested that Americans mark the anniversary of American independence in future years with “bonfires and illuminations.”

In that same Adamsian spirit, Pennsylvania residents today will stock up on bottle rockets, Roman candles, and firecrackers for the holiday weekend at Phantom Fireworks in North Lima, Ohio. Some will only buy sparklers. Others will spend thousands of dollars on the more extravagant stuff. Ohio will pocket the sales tax regardless.

Then it will make them swear to leave the state within 48 hours, fireworks in tow.

We’ll never know how Adams might have felt about Ohio’s law, but it seems fitting that in a country where many of the regional differences that existed 237 years ago still remain, we should celebrate our becoming “free and independent States” with fireworks, a product that sums up just how free and independent our states can be.

After all, fireworks are that rare category of product that is legal and regulated in some corners of the republic, and outright forbidden in others. Their status has made firework shops, often little more than tents or warehouses clad in garish colors and bombastic signage, a mainstay of the American road trip and a metric of cultural change as one crosses from state to state. It is said in North Carolina that you don’t need a welcome sign to know when you’ve reached South Carolina–just wait until you see the firework stores. (A saying easily confirmed by a Google Maps search.)

But it’s not as simple as one state selling fireworks that another won’t. In some cases, the market is designed to reap the tax benefit of firework sales while forcing the potentially harmful effects of their use—forest fires, emergency room visits—onto neighboring states.

But these laws, like the one in Ohio, only work assuming other states won’t also enact the same regulations.

A foolish assumption, as it turns out. Across the border from Ohio, in Pennsylvania, out-of-state shoppers can purchase a wide variety of aerial fireworks, whose potential for causing harm is greater than ground-based ones. Pennsylvanians, meanwhile, are limited to the latter kind. A similar setup exists to the south, in West Virginia.

A delicate dance thus ensues every summer, when buyers cross state lines to buy the same fireworks their own states will only sell to outsiders.

It’s not an efficient system, for sure. But it also highlights a useful workaround inherent in our federalist system that allows everyone to go home happy.

State governments can claim to have fulfilled their obligation to prohibit dangerous fireworks from being set off in their state by restricting who can buy them—or demanding that they leave the state.

Meanwhile, buyers appreciate a no-questions-asked sale that saves them from the permitting and insurance they would have to go through if there were a regulated in-state firework market.

With firework injury data largely self-reported on a state-by-state basis, it is difficult to measure how much the residents of states where fireworks are illegal are made to suffer for their proximity to states eager to sell.

But perhaps in response to the clear popular demand for fireworks, law enforcement in the stricter states remains, in the grand scheme of things, practically nonexistent.

In New Jersey, for example, where all fireworks are illegal, the state police claim to confiscate between 500 and 1,000 cases of fireworks every year from motorists coming from Pennsylvania. But with over a dozen firework stores doing business just over the state line, the figure is clearly just a drop in the bucket.

That’s why, come nightfall this Fourth of July, many Americans will ignore the fact that our “bonfires and illuminations” caused 9,600 injuries and 17,800 fires in 2011. They’ll skip the country’s 14,000 professionally run fireworks shows, break state laws, and, in the words of one convenience store clerk from The Simpsons, celebrate the independence of our country by blowing up a small part of it.