After a book and a movie told author Cheryl Strayed’s tail of hiking through the 2,200-mile-long Pacific Crest Trail (PCT), the system received such a flood of hiker interest that the trail association announced a permitting system to limit hikers. Now, concerns have been raised that the Appalachian Trail (AT), on the other side of the country, needs a similar limit on its thru-hikers, Kathryn Miles reports for Outside.

"The AT model is based on unlimited growth," says Jensen Bissell, the director of Baxter State Park, at the northern end of the trail in Maine. "The trail's usage has already increased several hundred percent [in the past 25 years]. We don’t see any mechanism in the management model to prevent it from increasing another 2,000 percent."

Already, the trail system had grappled with a surge of hikers after Bill Bryson published his Walk in the Woods in 1998. But Cheryl Strayed’s Wild boost to the PCT also affected the AT. And September 2 marks the release of a film version of Bryson’s account. Bissell and others up and down the 2,168-mile trail are concerned that the latest thru-hikers include too many that are breaking rules — they carry open containers of alcohol, camp illegally and forge service dog papers to bring their pets with them.

Miles writes:

No one could have predicted in 1921, when the trail was first conceived, how popular it would become today or what kind of abuse it would endure. Only three hikers completed the trail in the 1940s, according to the trail conservancy. The numbers were manageable in the 1970s when, during the course of the entire decade, a total of 775 thru-hikers completed the trail (for an average of about 77 hikers per year). Compare that to 2014, when more than 2,800 thru-hikers started the trail and an estimated three-to-four million people hiked a section of it.

The concern isn’t just over the changing nature of the trail experience — hiking it was once a very solitary undertaking and now a reporter for the Associated Press calls it "a rolling, months-long frat party," (via the Toledo Blade). All those people are also impacting the environment on the trail. The Katahdin Butterfly was once prolific at the trail’s terminus in Maine, but now it is endangered. The decline is in part, experts say, due to increasing foot traffic that wore the butterflies' meadow on Mount Katahdin bare.

The National Park Service commissioned biologist Jeff Marion to assess the trail over three years, starting last year. He’s also worried: “There’s litter at shelters, people leaving used toilet paper right on the trail, hikers throwing used batteries into the fire,” he tells Outside. “I try to talk to them and they say they don’t care.”

Regional organizations are working to update shelters and repair trails for the anticipated effects of the Walk in the Woods movie. However, some worry that won't be enough to counteract the potential damage of too many hikers.