Just before sunset near Page, Ariz., a parade of humanity marched up the sandy, half-mile trail toward Horseshoe Bend. They had come from all over the world. Some carried boxes of McDonald’s Chicken McNuggets, others cradled chihuahuas and a few men hid engagement rings in their pockets. But just about everyone had one thing at the ready: a cellphone to snap a picture.

Horseshoe Bend is one of the American West’s most celebrated overlooks. From a sheer sandstone precipice just a few miles outside Grand Canyon National Park, visitors get a bird’s-eye view of the emerald Colorado River as it makes a U-turn 800 feet below. Hundreds of miles from any large city, and nestled in the heart of Southwest canyon country, Horseshoe Bend was once as lonely as it was beautiful.

“It was just a local place for family outings,” recalls Bill Diak, 73, who has lived in Page for 38 years and served three terms as its mayor. “But with the invention of the cellphone, things changed overnight.”

Horseshoe Bend is what happens when a patch of public land becomes #instagramfamous. Over the past decade, photos have spread like wildfire on social media, catching the 7,000 residents of Page and area land managers off guard.

According to Diak, visitation grew from a few thousand annual visitors historically to 100,000 in 2010 — the year Instagram was launched. By 2015, an estimated 750,000 people made the pilgrimage. This year, visitation is expected to reach 2 million.

Numbers used to peak in the summer, but tourists now stream in year-round — nearly 5,000 a day. And fame has come with a dark side. In May 2018, a Phoenix man fell to his death when he slipped off the cliff edge. In 2010, a Greek tourist died when a rock underneath him gave way, police said, as he took photos. Like the recent death of a couple taking photographs in Yosemite, the occurrences have raised troubling questions about what happens when nature goes viral.

“Social media is the No. 1 driver,” says Maschelle Zia, who manages Horseshoe Bend for the Glen Canyon National Recreation Area. “People don’t come here for solitude. They are looking for the iconic photo.”

Human invasion

Across America, national parks and public lands face a crisis of popularity. Technology, successful marketing and international tourism have brought a surge in visitation unlike anything seen before. In 2016 and 2017, the national parks saw an unprecedented 330.9 million visitors, the highest ever recorded. That’s not far off the U.S. population itself.

Backcountry trails are clogging up, mountain roads are thickening with traffic, picturesque vistas are morphing into selfie-taking scrums. And, in the process, what is most loved about them risks being lost.

“The least-studied mammal in Yellowstone is the most abundant: humans,” says Dan Wenk, the former superintendent of one the most chronically overcrowded parks in the system. In Yellowstone, America’s oldest national park, visitation has surged 40 percent since 2008, topping 4 million in 2017.

After 43 years in the National Park Service, Wenk is worried. “Our own species is having the greatest impact on the park, and the quality of the experience is becoming a casualty.”

Over a period of four months, from high summer to late autumn, The Guardian dispatched writers across the American West to examine how overcrowding is playing out at ground level. We found a brewing crisis: 2-mile-long “bison jams” in Yellowstone, fistfights in parking lots at Glacier, a small Colorado town overrun by millions of visitors.

Moreover, we found people wrestling with an existential question: What should a national park be in the modern age? Can parks embrace an unlimited number of visitors while retaining what made them, as the writer Wallace Stegner once put it, “the best idea we ever had”?

‘Bison jam’

In 1872, Yellowstone became the first national park in the world. In 1904, the first year for which visitation figures are available, 120,690 people visited the national parks, which by then included Mount Rainier, Sequoia and Yosemite. By the midcentury, that number swelled to tens of millions as more parks were added to the system and destination road trips became synonymous with American vacations.

But today the pace of visitation has outstripped resources. Much of the National Park Service’s infrastructure dates back to Mission 66, a $1 billion initiative undertaken in the 1950s and ’60s, and wasn’t built with modern crowds in mind.

Environmental challenges are burgeoning — recent research has found national parks bear the disproportionate brunt of climate change — and years of wear and tear have seen park maintenance fall woefully behind. The current backlog of necessary upgrades to roads, trails and buildings stands at more than $11 billion. Interior Secretary Ryan Zinke’s attempt to sharply increase entry fees at the busiest parks to pay for repairs proved so unpopular it had to be walked back in April.

Traffic congestion has become one of the most visible consequences of overcrowding and underfunding, with some locations seeing tens of thousands of cars a day during peak months.

In Yosemite, despite a shuttle system, the park warns summer visitors to expect two- to three-hour delays entering Yosemite Valley. In Yellowstone, epic bottlenecks are frequent. Famed for its grizzly bears, gray wolves and bison herds, the park is arguably “wilder” than it was 50 years ago, thanks to conservation work. But this re-wilding has meant animal sightings routinely cause gridlock along its two-lane roads.

On a recent August day in Hayden Valley, a “bison jam” stretched nearly 2 miles long. As the herd moved steadily across the road, a scene of frantic commotion began to unfold. Travelers excitedly scrambled from their vehicles. Bison passed within inches, even brushing up against cars. Some tourists temporarily abandoned their vehicles in the hope of getting close enough for a photo.

Impatient motorists tooted their horns as park rangers tried to bring order. “My job is to manage people, not animals, and I try not to get upset,” said one in uniform. “Most visitors just don’t know how to behave in a wild place.”

But the bison weren’t the only drama. In the Lamar Valley, a pack of wolves just visible in the distance drew a swarm of vehicles into a turnout. People poured out, leaving their cars parked catawampus, blocking traffic in both directions.

Sometimes travelers get more of a souvenir than they bargained for. Last summer saw a handful of visitors gored or kicked by bison and elk when they ventured too close. Meanwhile, a video of a man taunting a bison went viral, and citations have been issued to troublemakers who illegally flew drones and tossed rocks and debris into Yellowstone’s sensitive geothermal features, which risks destroying them forever.

Wenk acknowledges rangers feel overwhelmed. “We’re exceeding the carrying capacity, and because of it, damage is being caused to park resources,” he says. There has been a 90 percent increase in vehicle accidents, a 60 percent bump in calls for ambulance services and a 130 percent rise in searches and rescues, according to the park. And while visitation has swelled, staffing, because of budget limitations, has remained the same.

Traffic woes aren’t confined to park roads. At Glacier National Park in Montana (annual visitation: 3.3 million), parking lots, too, have seen tense standoffs.

The Logan Pass Visitor Center dates back to the Mission 66 era. Perched at the top of Going-to-the-Sun Road, a precarious mountain artery that makes an appearance in the opening scene of “The Shining,” the center offers access to two of Glacier’s most popular trails — and just 231 parking spots.

“It’s a tough situation,” says Gary Cassier, a visitor from Kalispell, Mont., whose wife was still circling in their car, one of many seeking a spot. Looking out over the alpine meadows and near-vertical slopes, he observed: “Nobody wants to see a multilevel parking garage here.”

Sometimes the battle for a spot turns physical.

“We get fistfights in the parking lot,” says Emlon Stanton, a visitor service assistant. Some visitors even try to claim a spot for their groups on foot. “People get out of their vehicle, jump into a space and stand there,” explains Stanton. “Then somebody tries to pull in and bumps ’em.”

Stanton and other park workers try to prevent such episodes by imposing “soft closures” on the lot — placing traffic cones across its entrance and telling visitors to find parking at the next pullout, 3 miles away, and take a shuttle back. These closures can happen three to five times a day.

“From a staff perspective, it’s hard,” says park spokeswoman Lauren Alley. “‘Service’ is in our name, and to tell people, over and over, all day long, ‘We’re full, you’ll have to wait’ … it’s a real challenge.”

Toilet toils

It’s late summer on the Yellowstone River, just north of Gardiner, Mont. Some anglers stand around their boat trailer, sipping beers and rigging fly rods in the late-morning sun as they wait their turn to launch into the water.

This gravel boat ramp sees a lot of action. But not far off, something stinks. It’s something everybody uses, and something that’s been a headache for forest officials lately: a toilet.

Dealing with human waste has become a herculean undertaking for parks, one that is often hidden from view. In Zion National Park, two outhouses near Angels Landing that were described by one writer as reminiscent of “an open sewer” have to be emptied by helicopter at a cost of $20,000 annually. In Colorado, Rocky Mountain National Park churns through more than 1,800 miles of toilet paper a year. Yellowstone spent $28,000 on hand sanitizer last summer alone, according to a park official.

As waste mounts, finding someone to take care of it becomes more difficult. The Custer Gallatin National Forest, which stretches from the town of West Yellowstone, Mont., to South Dakota, exemplifies this conundrum.

There are more than 200 vault toilets across the Custer Gallatin, small rooms with a single pot over a large septic tank. Signs on the doors remind users not to throw trash in them because it makes vault pumping difficult.

In such remote places, the cost of servicing toilets has soared. In 2013, forest officials budgeted roughly $32,000 for toilet pumping across the Custer and Gallatin national forests (the two forests combined in 2014). So far in 2018, it has cost nearly $80,000. And that’s only the pumping in “priority locations,” explains Lauren Oswald, the recreation program manager for the Custer Gallatin.

Beyond the hefty price tag, the logistics of finding a private contractor to do the job have become more fraught, especially as towns like Bozeman grow and construction sites hire away the possible candidates. The toilet at the boat ramp is serviced by a company based in Hardin, Mont. — more than 200 miles away.

Nearby Yellowstone has waste worries, too. Bethany Gassman, a park spokeswoman, says park staff pumped 248,889 gallons from its 153 vault toilets and other septic systems in 2017, a 19 percent increase over 2016. Visitors also run through an average of 1,710 toilet paper rolls a day.

The problem of managing human waste extends to the backcountry — areas far from roads and development and accessible only by trails. Forest staffers have seen an increase in improperly managed excrement — unburied poop — in popular wilderness areas and unofficial campsites. The problem, Oswald says, is that some people don’t seem to care how they leave the landscape once they’re done with it.

Forest staffers often face the unenviable task of dealing with what slob campers leave behind. It’s the kind of work that sanitation workers are hired for in major cities, not what you’d expect among the wooded peaks and meadowed valleys of Montana.

“They pick up all garbage, whether it’s toilet paper or diapers or beer bottles,” Oswald says of the cleanup missions. “And generally if they come upon human waste, they try to deal with it by burying it at an appropriate depth.”

Zion’s overflow

Once parks were the ultimate place to disconnect from the modern world. But today visitors have fresh expectations — and in accommodating these new demands, some say parks are unwittingly driving the very behavior that’s spoiling them.

On Yosemite’s expansive mountainsides, one redwood stands out among the rest. It’s a little bit taller, a little bit too uniform. A metallic shimmer glints in the sun from beneath its branches, colored green and brown to match its neighbors. But this camouflage masks its true role: coating the wilderness in Wi-Fi.

This tree is helping to usher in a new era in Yosemite. And it’s not alone. Grand Tetons, Mount Rainier, Yellowstone and Zion are all being wired with internet and cell service as part of a plan to attract a new generation of parkgoers. In Yosemite, there are six towers already constructed, with plans underway for close to a dozen more.

The rapid modernization of Yosemite (annual visitation 4.3 million) is evident at Base Camp Eatery, one of the park’s newest food spots. Here, touch screens enable hungry hikers to order drinks and snacks and access instant information about park activities. There’s even a newly opened — and particularly controversial — branch of Starbucks.

“The ways people find out about — and visit — parks is changing,” Lena McDowall, the National Park Service deputy director, told the Senate subcommittee on national parks last year. Many see meeting the needs of millennials as critical to keeping parks politically relevant amid funding challenges and the uncertainty of climate change.

But the move may come at a cost. “Why come to a national park as opposed to Disneyland? Because you get to confront natural wonders,” says Jeff Ruch, the executive director of PEER, an environmental advocacy organization that has spent years opposing National Park Service plans for expanding cell tower construction. “But if you interpose electronic devices in our view, you miss that.”

Technological transformation is having unexpected consequences on the landscapes that surround national parks, too. In Utah, visitors are arriving in remarkable numbers to admire its photogenic landscapes — turning Zion, Bryce Canyon and Arches into some of the busiest in the country.

But the increasing squeeze has pushed many to seek thrills elsewhere. Take Kanarraville Falls, just an hour outside southern Zion. Here visitors traverse a narrow, twisting canyon carved through pink-purple sandstone along a series of makeshift ladders, finally arriving at a beautiful waterfall: a taste of Zion’s magical slot canyons but without the crowds. Or at least it used to be.

Social media posts have been blamed for ruining Kanarraville Falls, once a hidden gem but now featured in countless Instagram posts. Bottlenecks can back up for an hour or more at the ladders, rescue teams are dispatched regularly to retrieve injured hikers, and stream banks are eroding and littered with trash.

For the nearby town of Kanarraville (population 378), the situation has become untenable. Visitors, who routinely double the town’s population, are tramping through a watershed the town taps for drinking water. “The environment can’t handle that many people walking in and out of there,” says Tyler Allred, a Town Council member. “It needs a chance to recover.”

Kanarraville leaders are doing what they can: The town now charges a $9-per-head fee for hikers, thanks to an arrangement with the state and federal officials.

It’s an experiment that could be replicated elsewhere. But so far the fee hasn’t done much to slow daily traffic, according to Allred. Annual visitation last year was estimated at between 40,000 and 60,000. The next step may be to impose a daily limit on visitors.

Stephen King slept here

Kanarraville is not the only town where tourism is taking a toll. Moab, outside Arches National Park, has become a byword for congestion. In California, locals bemoan the Airbnb-ification of Joshua Tree — an artsy, isolated desert community now overrun by out-of-towners fond of drones and late-night parties.

In Estes Park, just outside the entrance to Rocky Mountain National Park, the problems have become especially acute. It’s 90 minutes from the fast-growing city of Denver, and urbanites flock here in droves for the alpine tundra and soaring, snowcapped mountains.

In the summer months, Estes balloons from its winter population of about 7,000 to a barely contained mass of as many as 3 million people who stream through downtown in search of themed T-shirts, American Indian trinkets and a brewpub libation.

For 82-year-old Paula Steige, the crush is almost unbearable. Traffic makes getting around downtown a logistical ordeal and solutions offered by the town — including free shuttle buses — offer only minor relief.

“Oftentimes it seems we are in crisis mode, just trying to figure out how to get around. It’s especially bad for people trying to get to and from the park,” Steige says. “And there just doesn’t seem to be a solution to all the overcrowding.”

Steige can’t join those longtime residents who escape to other locales during the summer because she owns and operates the Macdonald Book Shop, started by her grandparents in 1908. She also knows that, like other shop owners, she owes her livelihood to the nearby national park.

“The park is, of course, the reason the whole town thrives,” she says. “The park is the reason the town does well or it goes badly.”

Estes Park, too, has a famous link to “The Shining”: It’s home to the Stanley Hotel, the remote establishment that inspired the horror classic. Author Stephen King spent a night here in 1974. The Stanley now pulls in nearly 400,000 annual visitors, from ghost hunters attending tours and seances to horror fans hoping to stay in King’s room. The overcrowding galled one recent Stanley visitor. “We went for a seance but so many tourists were crowding around, we couldn’t hear anything,” says the man, who was visiting from Minnesota.

Police activity in Estes Park is ticking up, too. Police say calls earlier this year jumped nearly 23 percent over the same period in 2017. The park has also seen a dramatic rise in drug citations and arrests, fueled mostly by a misunderstanding of Colorado’s drug laws, park rangers say. Pot is legal in Colorado and therefore the town of Estes Park, but not at the national park itself, which is on federal property and where the state’s pot laws don’t apply.

“We see a lot more flagrant violations of pot use as well as driving under the influence by people who don’t know or don’t care about the law,” says Kyle Patterson, a park spokeswoman. “I think all of that comes from the fact we are rapidly transforming into an urban park.”

New limits

While Wallace Stegner’s notion that parks are “America’s best idea” has become synonymous with the nation’s love for them, there’s a little more to his famous 1983 line. The Pulitzer Prize winner went on to describe the parks as a mirror for America’s national character: “They reflect us at our best rather than our worst.”

Considering the problems besetting the parks, his sentiment now seems open to question.

Back in Yellowstone, resource experts say the park is racing headlong toward a reality some might consider sacrilege: limits on people. One top park service official, who did not want to be identified, said daily limits on traffic entering Yellowstone, which could be achieved through a reservation system, were long overdue.

On the foggy coast of Northern California, one spot has already taken the plunge. Muir Woods — named for John Muir, a renowned conservationist and one of the earliest advocates for national parks — is home to ancient groves of towering redwoods. The forest is tiny by park standards — 560 acres — yet more than a million come each year to experience its majestic calm.

Hundreds of parked cars once choked the narrow road leading toward the entrance, threatening watershed and wildlife, causing headaches for nearby residents, and creating dangerous situations for drivers and pedestrians walking on the roadside.

That’s why, at the beginning of this year, it became the first to introduce a new parking reservation system that requires all visitors to buy their spots before arriving. Street parking has been banned — and the number of parking spots has been reduced by roughly 70 percent.

While officials say it’s too early to tell, estimates show that the reservation system will reduce annual numbers by about 200,000. Park representatives say they hope it will curb crowding by helping people plan their trips for less-busy time slots. So far, it seems to be working.

On a drizzling midweek afternoon, nearing the end of summer, both Muir Woods parking lots were full. Near the entrance, the giggle and chatter of excited children mingled with the sounds of waterfalls and bird calls. Stroller wheels thudded rhythmically along the planked wooden boardwalk, echoing through the grove. But a few paces deeper, the throngs thinned, and visitors could find a semblance of solitude among the ancient trees.

“Even with a lot of people here, there are little pockets of silence you can find,” said Meghan Grady, who lives in nearby San Francisco. “We sat and shut our eyes for a little bit just to listen.”

It is experiences like these that park officials hope to protect. If they are successful, others may follow suit. Parks including Zion, Arches and Acadia are all urgently considering reservation-only systems.

But as officials weigh large-scale changes, which can take years to research and implement, others point to behavior changes that can be made right now. For instance, a growing cohort of photographers, social media influencers and conservationists is pushing back on geotagging — using GPS to share the precise location in which a photo was taken. Leave No Trace, a nationwide organization promoting outdoor ethics, is helping to spearhead the movement. In June, it released new guidance on using social media responsibly in nature. Dana Watts, the executive director, says the move was the result of feedback from land management agencies, the park service, the Bureau of Land Management and the public.

Avoid geotagging specific locations, she advises, and think carefully before posting a selfie with wildlife. “Everyone wants to capture that picture, but people tend to get way too close,” she says. “If you are posting that, you are encouraging others to do the same.

“The biggest thing we are asking people to do," she adds, “is stop and think.”

‘It is just going to keep growing’

At Horseshoe Bend, the Instagram crowds aren’t going anywhere soon. Beginning in April, the city of Page will start charging a $10-per-car entrance fee that will go directly to pay for management of the area. But Ziua, the Glen Canyon National Recreational Area manager, expects demand to steadily increase anyway. “Between 2015 and 2017, visitation doubled,” she says. “I think it is just going to keep growing.”

In the meantime, managers are doing what they can to improve safety and protect the landscape. A metal railing now cuts across the cliff’s edge to prevent people from tumbling off. Vault toilets were added two years ago. What was once a 100-square-foot dirt parking lot has been expanded this year to hold up to 300 cars.

On a November evening, people lined up to watch the sky turn from orange to hot pink as the sun descended. Jenny Caiazzo, 24, was visiting from Denver, touring Southwest national parks with her friend. “Now that I’m here, I see it’s even more beautiful than the pictures.”

Visitors admired the view from the rim. “It’s breathtaking," said Brett Rycen, a visitor from Australia on a coast-to-coast tour with his wife and daughter. “We’ve been Snapchatting a lot. We want our friends to know what we are experiencing.”

Nearby, Tristan Fabic and Cecille Lim from Los Angeles had just gotten engaged. “This is the place where I wanted to propose,” Fabic said. “I saw it on Instagram and thought it would be really cool.”

Reporting: Charlotte Simmonds in Oakland, Calif.; Annette McGivney in Horseshoe Bend, Ariz.; Todd Wilkinson in Yellowstone National Park, Wyo.; Patrick Reilly in Glacier National Park, Mont.; Brian Maffly in Salt Lake City; Gabrielle Cannon in Yosemite National Park and Muir Woods National Monument, Calif.; Michael Wright in Gardiner, Mont.; and Monte Whaley in Estes Park, Colo. This story originally appeared in The Guardian as part of its two-year series This Land Is Your Land, with support from the Society of Environmental Journalists. It was reported and published in collaboration with The Denver Post, the Missoulian, The Salt Lake Tribune and the Bozeman Daily Chronicle.