Nearly three weeks into the government shutdown, some of America's national parks are starting to get a bit rank. Access is free, since there are no employees to collect the typical $35-per-vehicle entrance fees, but that comes with the trade-off of there being no employees to empty trash bins or clean toilets either.

But at Yellowstone National Park, National Public Radio reports, local businesses are chipping in to make sure the bathrooms get cleaned, the roads get plowed, and the tourists keep coming. Even in the middle of winter, the park gets an estimated 20,000 visitors per month—and those hardy folks want to rent snowmobiles, hire tour guides, and take sightseeing trips. The private-sector businesses that thrive on those tourist dollars have a pretty strong incentive to make sure Yellowstone remains accessible.

Xanterra Parks and Resorts, which runs the only hotels inside Yellowstone that remain open during the winter, is leading the effort to cover the $7,500 daily tab for keeping the roads plowed and the snowmobile trails groomed during the shutdown, according to NPR. Thirteen other private businesses that offer tours of the park are chipping in $300 a day to help cover that expense.

Meanwhile, Xanterra has some of its own employees assigned to clean park bathrooms during the shutdown, and snowmobile tour guides are packing their own toilet paper for customers to use.

In all, it seems like a pretty straightforward lesson about how private businesses will respond to changing market conditions and incentives. While some of the business owners profiled by NPR suggest they are chipping in to keep the park open due to altruistic concerns—"it should be open, and services should be there, because it is the people's park," says one—the bottom line is likely the bottom line. Keeping the park accessible means those businesses can continue to profit off tourists, government shutdown or not.

That doesn't mean that altruistic motivations don't exist, of course. In Washington, D.C., a group of libertarians volunteered time on Saturday to clean up land that's usually maintained by the National Park Service. "It's an example of us practicing what we preach. We want the private sector to step up when government can't, so that's what we're doing here," Joseph Bishop-Henchman, chairman of the Libertarian Party of the District of Columbia, told local media.

Those efforts are praiseworthy, but ultimately less sustainable than the profit motive that's helping keep Yellowstone open.

Indeed, those profit motives exist with or without a government shutdown. According to the National Park Service, the 331 million visitors to national parks during 2017 contributed an estimated $18.2 billion to local economies within 60 miles of the parks. All that spending supported 306,000 jobs. The federal government spends about $3 billion on the National Park Service each year, but those private economies based in and around the parks is six times larger. That's a powerful incentive to keep things running even if the government isn't.

There's also probably a useful lesson here about what the privatization of national parks would look like. Rather than the corporatized dystopia of environmentalist nightmares, removing the government from the equation would allow businesses that have a vested interest in maintaining and protecting America's natural splendor to do exactly that—and would prevent the parks from being caught up in the unrelated drama of whatever nonsense is happening in Washington, D.C.