On Trails
PROLOGUE

ONCE, YEARS AGO, I left home looking for a grand adventure and spent five months staring at mud. It was the spring of 2009, and I had set out to walk the full length of the Appalachian Trail from Georgia to Maine. My departure date was timed so that I would transition seamlessly from a mild southern spring to a balmy northern summer, but for some reason the warmth never arrived. It stayed cool that year, rained often. Newspapers likened it to the freak summer of 1816, when cornfields froze to their roots, pink snow fell over Italy, and a young Mary Shelley, locked up in a gloomy villa in Switzerland, began to dream of monsters. My memories of the hike consist chiefly of wet stone and black earth. The vistas from many of the mountaintops were blotted out. Shrouded in mist, rain hood up, eyes downcast, mile after mile, month after month, I had little else to do but study the trail beneath my nose with Talmudic intensity.

In his novel The Dharma Bums, Jack Kerouac refers to this kind of walking as “the meditation of the trail.” Japhy Ryder, a character modeled after the Zen poet Gary Snyder, advises his friend to “walk along looking at the trail at your feet and don’t look about and just fall into a trance as the ground zips by.” Trails are seldom looked at this intently. When hikers want to complain about a particularly rough stretch of trail, we gripe that we spent the whole day looking down at our feet. We prefer to look up, away, off into the distance. Ideally, a trail should function like a discreet aide, gracefully ushering us through the world while still preserving our sense of agency and independence. Perhaps this is why, for virtually all of literary history, trails have remained in the periphery of our gaze, down at the bottommost edge of the frame: they have been, quite literally, beneath our concern.

As hundreds—and then thousands—of miles of trail passed beneath my eyes, I began to ponder the meaning of this endless scrawl. Who created it? Why does it exist? Why, moreover, does any trail?

Even after I reached the end of the AT, these questions followed me around. Spurred on by them, and sensing in some vague way that they might lead to new intellectual ground, I began to search for the deeper meaning of trails. I spent years looking for answers, which led me to yet bigger questions: Why did animal life begin to move in the first place? How does any creature start to make sense of the world? Why do some individuals lead and others follow? How did we humans come to mold our planet into its current shape? Piece by piece, I began to cobble together a panoramic view of how pathways act as an essential guiding force on this planet: on every scale of life, from microscopic cells to herds of elephants, creatures can be found relying on trails to reduce an overwhelming array of options to a single expeditious route. Without trails, we would be lost.

My quest to find the nature of trails often proved trickier than I had expected. Modern hiking trails loudly announce their presence with brightly painted signs and blazes, but older trails are more inconspicuous. The footpaths of some ancient indigenous societies, like the Cherokee, were no more than a few inches wide. When Europeans invaded North America, they slowly widened parts of the native trail network, first to accommodate horses, then wagons, then automobiles. Now, much of that network is buried beneath modern roadways, though remnants of the old trail system can still be found when you know where—and how—to look.

Other trails are yet more obscure. The trails of some woodland mammals dimple the underbrush so faintly that only an experienced tracker can point them out. Ants nose along chemical pathways that are wholly invisible. (One trick to seeing them, I learned, is to sprinkle the area with lycopodium, the same powder police use to dust for fingerprints.) A few trails are tucked away underground: termites and naked mole-rats carve tunnels through the earth, marking them with traces of pheromones to keep their bearings. Finer still are the tangled neural pathways within a single human brain, which are so multitudinous that even the world’s most advanced computers cannot yet map them all. Technology, meanwhile, is busy knitting itself into an intricate network of pathways, dug deep underfoot and strung ethereally overhead, so that information can race across continents.

I learned that the soul of a trail—its trail-ness—is not bound up in dirt and rocks; it is immaterial, evanescent, as fluid as air. The essence lies in its function: how it continuously evolves to serve the needs of its users. We tend to glorify trailblazers—those hardy souls who strike out across uncharted territory, both figurative and physical—but followers play an equally important role in creating a trail. They shave off unnecessary bends and brush away obstructions, improving the trail with each trip. It is thanks to the actions of these walkers that the trail becomes, in the words of Wendell Berry, “the perfect adaptation, through experience and familiarity, of movement to place.” In bewildering times—when all the old ways seem to be dissolving into mire—it serves us well to turn our eyes earthward and study the oft-overlooked wisdom beneath our feet.

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I was ten years old when I first glimpsed that a trail could be something more than a strip of bare dirt. That summer, my parents shipped me off to a small, antiquated summer camp in Maine called Pine Island, where there was no electricity or running water, only kerosene lanterns and cold lake. During the second of my six weeks there, a handful of us boys were loaded into a van and driven many hours away to the base of Mount Washington, for what was to be my first backpacking trip. As a child of the concretized prairies of suburban Illinois, I was apprehensive. The act of lugging a heavy pack through the mountains looked suspiciously like one of those penitent rituals that adults sometimes forced themselves to perform, like visiting distant relatives or eating crusts of bread.

I was wrong, though; it was worse. Our counselors had allotted us three days to climb the eight miles to the top of Mount Washington and back down, which should have been ample time. But the trail was steep, and I was scrawny. My backpack—a heavy, ill-fitting, aluminum-­framed Kelty—resembled a piece of full-body orthodontia. After only an hour of climbing the wide rocky trail leading up Tuckerman Ravine, my stiff new leather boots had already begun to blister my toes and rasp the skin from my heels. A hot liquid ache perfused the muscles of my back. When my counselors weren’t looking, I made pleading, pained faces at passing strangers, as if this were all part of some elaborate kidnapping. That night, as I lay in my sleeping bag in the lean-to, I considered the logistics of an escape.

On the second morning, a gray rain blew in. Instead of summiting the peak, which our counselors deemed unsafe, we took a long hike around the southern flank of the mountain. We left our packs back at the shelter, each of us carrying only a single water bottle and a pocketful of snacks. Free from the dreaded weight of my pack, warm inside my rubberized rain poncho, I began to enjoy myself. I inhaled the fir-sweet air, exhaled fog. The forest gave off a faint chlorophyllic glow.

We walked in single file, floating through the trees like little ghosts. After an hour or two, we rose above the tree line and entered a realm of lichen-crusted rock and white mist. The trails around the mountain branched and twined. At the juncture with the Crawford Path, one of our counselors announced that we were turning onto a leg of the Appalachian Trail. His tone suggested we were meant to be impressed. I had heard that name before, but I wasn’t sure what it meant. The path beneath our feet, he explained, followed the spine of the Appalachians north to Maine and south all the way to the state of Georgia, almost two thousand miles away.

I still recall the tingle of wonder I felt upon hearing these words. The plain-looking trail beneath my feet had suddenly grown to colossal scale. It was as if I had dived down into the camp lake and discovered the slow, undulant vastness of a blue whale. Small as I felt back then, it was a thrill to grasp something so immense, if only by the very tip of its tail.

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I kept hiking. It got easier—or rather, I got tougher. My pack and boots softened until they slid into place with the dry fluidity of an old baseball glove. I learned to move nimbly beneath a heavy load and push on for hours without breaks. I also came to savor the satisfaction of dropping my pack at the end of a long day: the warm animal weight would fall coolly away, and I would rise from my burden with a weird heliated feeling, as if my toes were merely grazing the dirt.

Hiking proved to be the perfect pastime for a free-floating kid like me. My mother once gave me a leather-bound journal that was meant to have my name embossed in gold along the spine, but instead the printer erroneously engraved the words ROBERT MOON. The mistake was oddly fitting. Growing up, I often felt extraterrestrial. It wasn’t that I was lonely or ostracized; I just never felt fully at home. Before I went off to college, no one knew I was gay, and I knew no other gay people. I did my best to blend in. Each year I would dutifully put on a suit and tie for the spring formal, the cotillion, or the prom. I donned athletic uniforms, first-date uniforms, drinking-pilfered-cans-of-Old-Style-in-a-friend’s-basement uniforms. All the while, though, part of me wondered: What’s the point of this elaborately costumed performance we put on?

In my family I was the youngest child by nearly a decade. My parents, who were already in their forties by the time I was born, granted me an unusual amount of freedom. I could have run wild. Instead, I spent much of my time in my room reading books, which, I discovered, was like running away from home, minus the risk and parental heartache. And so, from the third grade on, I burned through books the way a chain-smoker smokes, picking up one even as I was extinguishing the last.

The book that kicked off my habit in earnest was a flimsy paperback copy of Little House in the Big Woods. I learned that my home, in northern Illinois, was just a few hundred miles southeast of where the book’s author, Laura Ingalls Wilder, was born in 1867. However, her descriptions of the Big Woods of Wisconsin were wholly foreign to me. “As far as a man could go to the north in a day, or a week, or a whole month, there was nothing but woods,” she wrote. “There were no houses. There were no roads. There were no people. There were only trees and the wild animals who had their homes among them.” I was intoxicated by Ingalls’s sense of isolation and self-reliance.

I don’t remember how many of the Little House books I read in a row, but it was enough to require an intervention from my teacher, who gently suggested I move on to something else. In the coming years I progressed from Little House to Hatchet to Walden to A Sand County Almanac to Pilgrim at Tinker Creek. I enjoyed lingering over the minutiae of a life spent outdoors. During my first summer at Pine Island, I discovered a parallel genre of wilderness adventure books: first the boyish yarns of Mark Twain and Jack London, then the alpine reveries of John Muir, the Antarctic agonies of Ernest Shackleton, and the existential odysseys of Robyn Davidson and Bruce Chatwin.

These two lineages of outdoor writers were roughly divided between those who were deeply rooted to a piece of land and those who were proudly untethered. I preferred the drifters. I held no profound connection to my land, my ancestors, my culture, my community, my gender, or my race. I was raised without religion, and without hatred of religion. My family was diffuse: my parents, two Texans living in the frigid North, were already divorced by the time I was in the first grade; not long after, my two older sisters went away to college and never moved back. A vague restlessness seemed to run in our blood.

Nine months out of every year I drifted through the halls of one academic institution after another, changing costumes, learning new dialects, faking fluency. It was only during the summers, on a series of ever-lengthening sojourns in the wilderness, that I felt wholly natural. I worked my way up from the Appalachians to the mighty Rockies, then to the Beartooths, the Winds, the snowy behemoths of the Alaska Range, and, later, high-altitude peaks ranging from Mexico to Argentina. Up there, far from etiquette or ritual, I could walk unscrutinized, unbound.

For two summers in college I took a job back at Pine Island leading kids on short hikes through the Appalachians. On trips along the AT I would occasionally bump into hikers who were attempting to walk the trail’s full length in a single, mammoth, months-long effort. These “thru-hikers” were easy to spot: They introduced themselves with odd “trail names,” ate ravenously, and walked with a light, lupine gait. I was intimidated by them, but also envious. They resembled the rock musicians of an idealized past—the same long hair, the same wild beards, the same wasted physiques, the same esoteric argot, the same peripatetic lifestyle, the same faint, vain awareness of being, in a way, heroic.

I sometimes talked with these thru-hikers, plying them with chunks of cheese or handfuls of candy. I remember one old man who had hiked the whole trail in a Scottish kilt and sandals, and a young man who carried no tent, but a full feather pillow. A few of them proselytized zealously for one church or another, while others spoke of preparing for a looming ecological apocalypse. Many of the people I talked to were between jobs, between schools, or between marriages. I met soldiers returning from war and people recovering from a death in the family. Certain stock phrases were repeated. “I needed some time to clear my head,” they said, or “I knew this might be my last chance.” One summer during college, I told a young thru-­hiker that I hoped to make an attempt someday. “Drop out,” he told me flatly. “Do it now.”

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I did not drop out. I was too careful for that. In 2008 I moved to New York, where I worked a series of low-paying jobs. In my free time I planned my thru-hike. I read guidebooks and online message boards, drew up tentative itineraries. Less than a year later I was ready to embark.

Unlike many people, I had no clear impetus for going on a long hike, no inciting incident. I wasn’t grieving a death or recovering from drug addiction. I wasn’t fleeing anything. I had never been to war. I wasn’t depressed. I was maybe only a little insane. My thru-hike was not an attempt to find myself, find peace, or find God.

Perhaps, as they say, I simply needed some time to clear my head; perhaps I knew this might be my last chance. Both were mostly true, as clichés often are. I also wanted to find out what it would be like to spend months on end in the wilderness, to live in a prolonged state of freedom. But more than that, I think I wanted to answer a challenge that had loomed over me since childhood. When I was small and frail, hiking the whole trail had seemed a herculean task. As I grew, its impossibility became precisely its appeal.

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Over the years, I had picked up some useful tips from the thru-hikers I’d met. Above all, I knew that weight was the enemy of a successful thru-hike, so I retired my trusty old pack and invested in a new ultralight one. Then I traded in my bulky tent for a hammock, bought an airy goose-down sleeping bag, and exchanged my leather boots for a pair of trail running shoes. I pared my medkit down to a few anti-­diarrheal pills, some iodine swabs, a thumb-sized roll of duct tape, and a safety pin. I replaced my white gas stove with one made out of two aluminum Coke cans, which weighed practically nothing. When I crammed all of my gear into my new pack and lifted it for the first time, I was amazed and slightly terrified. It seemed too insubstantial to house, clothe, and feed a human for five months.

So I wouldn’t be forced to live off an anemic diet of instant ramen and freeze-dried mashed potatoes, I began cooking heaping piles of nutritious slop (beans and brown rice, quinoa, couscous, whole wheat pasta with tomato sauce) and dehydrating them. I poured sparing amounts of olive oil and hot sauce into small plastic bottles. I filled plastic baggies with baking soda, Gold Bond, vitamins, and painkillers. I divided all of the supplies up into roughly five-day increments and packed them into fourteen cardboard boxes. Into each box, I also placed a chapbook of poetry or a heftier paperback novel that I had cut into slimmer volumes using a straight razor and packing tape.

I addressed these boxes to post offices along the trail—towns with names like Erwin, Hiawassee, Damascus, Caratunk, and (my favorite) Bland—and left them with my roommate to mail on specified dates. I quit my job. I sublet my apartment. I sold or gave away everything I could spare. Then, on a cold day in March, I flew down to Georgia.

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On the summit of Springer Mountain, the trail’s southern terminus, I was greeted by an old man who called himself Many Sleeps, a moniker he had reportedly earned while completing one of the slowest thru-hikes ever recorded. With his droopy eyes and long white beard, he looked like a nylon-clad Rip Van Winkle.

In his hand he held a clipboard. His job was to collect information from all the passing thru-hikers. He told me it had been a busy year: twelve thru-hikers had registered with him that day, and thirty-seven the day before. In total that spring, almost fifteen hundred people would set out from Springer aiming for Maine, though scarcely a quarter of them would make it.

There on the mountaintop, before starting my long-awaited hike, I paused to admire the land below: swells of frost-burned earth, fading from brown to gray to blue as they hazed out toward the horizon. The mountains dipped and heaved, jostled and collided. No towns or roads were in sight. It occurred to me that I would never be able to find my way to Maine without the trail. In this foreign, involuted terrain, I would have struggled to even make it to the next ridge. For the next five months, the trail would be my lifeline.

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On a trail, to walk is to follow. Like prostration or apprenticeship, trail walking both requires and instills a certain measure of humility. To keep my pack light, I had brought along no maps, no satellite assistance, only a thin guidebook and a cheap compass for emergencies. The trail was my only real source of navigation. So I clung to it, like Theseus tracing Ariadne’s unspooling ball of twine.

In my journal one night I wrote: “There are moments when you cannot help but feel that your life is being controlled by some not-­entirely-benevolent god. You skirt down a ridge only to climb it again; you climb a steep peak when there is an obvious route around it; you cross the same stream three times in the course of an hour, for no apparent reason, soaking your feet in the process. You do these things because someone, somewhere, decided that that’s where the trail must go.”

It was a creepy feeling, knowing that my decisions were not my own. In the first few weeks I often thought back to an anecdote I’d once heard about E. O. Wilson, the famed entomologist. In the late 1950s, to entertain visitors, Wilson used to write his name on a piece of paper with a special chemical liquid. Afterward, a swarm of fire ants would emerge from their nest and dutifully line up to spell out each letter of his name, like members of a marching band.

Wilson’s party trick was, in fact, the result of a major scientific breakthrough. For centuries, scientists had suspected that ants left invisible trails for one another, but Wilson was the first to pinpoint the source: a tiny, finger-shaped organ called the Dufour’s gland. When he extracted the gland from the abdomen of a fire ant and smeared it across a plate of glass, other fire ants immediately swarmed to it. (“They tumbled over one another in their haste to follow the path I had blazed for them,” Wilson recalled.) He later synthesized this trail pheromone, a single gallon of which, he estimated, could summon one trillion fire ants.

In 1968 a group of researchers in Gulfport, Mississippi, put a new twist on Wilson’s trick: They discovered that a certain species of termite will even follow a line drawn by a normal ballpoint pen, which contains glycol compounds that termites mistake for trail pheromones. (For some reason, termites prefer blue ink over black.) Ever since, science teachers have amused their students by drawing blue spirals on sheets of paper, while termites line up and confusedly circle toward nowhere.

On my hike, when the trail veered hard to the east or west, I would often wonder whether I too wasn’t being led in cruel circles. Seen in a certain light, trails represent a particularly grim form of determinism. “Man may turn which way he please, and undertake any thing whatsoever,” wrote Goethe, “he will always return to the path which nature has prescribed for him.” On the AT, this was certainly the case. Though I explored the surrounding woods and hitchhiked into towns, in the end I always came back to the trail. If uncertainty is the heart of adventure, I thought to myself, what kind of adventure was this?

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Northward I moved, through a gray southland spring. The trees were black scrags, the ground papered in old leaves. One morning in Tennessee, I awoke to find my hiking shoes bronzed in ice. In North Carolina, I hiked through knee-deep snow, then ankle-deep slush. The walking was hard, but then every few days, regardless of the terrain or the weather, I would experience the joy of slipping from the dark woods and ascending into the air and light.

In my second week on the trail I fell in with a tight little group of fellow thru-hikers. We happily traveled together for a few weeks. But upon reaching Virginia, I quickened my pace and lost them. Weeks or months later, whenever I slowed down or they sped up, I would bump into these friends again, as if by some miraculous coincidence. The miracle, of course, was the trail itself, which held us together in space like so many beads on a string.

Each of us adopted new trail names. Most people were given their names by fellow thru-hikers because of something they had said or done; my friend Snuggles, for example, had a habit of snuggling up against other hikers in the lean-tos at night to keep herself warm. Others picked names in an attempt to shape new, aspirational identities for themselves. A tense silver-haired woman renamed herself Serenity, while a timid young man called himself Joe Kickass; sure enough, over time, she seemed to grow incrementally calmer, and he more audacious.

A group of jolly older women christened me Spaceman, in reference to the astral appearance of my shiny, ultralight hiking gear. The name clicked. In the trail registers—notebooks located at regular intervals along the trail, meant for recordkeeping and note sharing—I began drawing a series of comic strips. The protagonist was a spaceman who had come down to Earth and somehow found himself navigating the strange customs, odd characters, and pseudo-wildernesses of the Appalachian Trail.

Once a week or so, a group of us thru-hikers would hitchhike into town together, find a cheap motel (sometimes piling six or eight people into a single room), and spend the day showering, washing our filthy clothes, drinking beer, eating impossible quantities of greasy food, and watching bad TV—glutting ourselves, like barbarians, on the meretricious pleasures of civilization. By the next morning we would be eager to get back on the trail, where we could sweat out the gunk and savor the clean air.

I had expected the trail to be a refuge for loners like me; the sense of community that formed among us scattered thru-hikers took me by surprise, and then grew to be one of the hike’s nectarine joys. We were bonded by common experience. Each of us knew how it felt to walk for weeks through hail and snow and rain. We starved; we gorged. We drank from waterfalls. In the Grayson Highlands, wild ponies licked the sweat from our legs. In the Smokies, black bears haunted our sleep. We had each faced down the same Cerberus of loneliness, boredom, and self-doubt, and we had learned that the only solution was to out-walk it.

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As I got to know my fellow thru-hikers—a motley pack of freedom seekers and nature worshipers and outright kooks—it struck me as odd that all of us had willingly confined ourselves to a single path. Most of us saw this hike as an interlude of wild freedom before we reentered the ever-tightening hedge maze of adult life. But complete freedom, it turned out, is not what a trail offers. Quite the opposite—a trail is a tactful reduction of options. The freedom of the trail is riverine, not oceanic.

To put it as simply as possible, a path is a way of making sense of the world. There are infinite ways to cross a landscape; the options are overwhelming, and pitfalls abound. The function of a path is to reduce this teeming chaos into an intelligible line. The ancient prophets and sages—most of whom lived in an era when footpaths provided the primary mode of transport—understood this fact intimately, which is why the foundational texts of nearly every major religion invoke the metaphor of the path. Zoroaster spoke often of the “paths” of enhancement, of enablement, and of enlightenment. The ancient Hindus too prescribed three margas, or paths, to attain spiritual liberation. Siddhartha Gautama preached the aryastangamarga, or the Noble Eightfold Path. The Tao literally means “the path.” The Hebrew word for Jewish law, halakhah, means “the walking”; the Arabic word for Islamic law, shariah, translates to “the path to the watering hole.”” The Bible, too, is crisscrossed with trails: “Ask for the ancient paths, where the good way is, and walk in it, and you shall find rest for your souls,” commanded the Lord to the idolaters. (Responded the idolaters: “We will not walk therein.”)

There are, it is often said by the more ecumenical prophets, many paths up the mountain. So long as it helps a person navigate the world and seek out what is good, a path, by definition, has value. It is rare to run across a spiritual leader preaching that there are no paths to enlightenment. Some of the Zen masters came close, though even the great Dogen stated that meditation “is the straight path of the Buddha way.” The Indian philosopher Jiddu Krishnamurti stands out in this regard. “Truth has no path,” he wrote. “All authority of any kind, especially in the field of thought and understanding, is the most destructive, evil thing.” Unsurprisingly, his path of pathlessness attracted fewer adherents than the reassuringly detailed instructions of Muhammad or Confucius. Lost in the howling landscapes of life, most people will choose the confinement of a path to the dizzying freedom of an unmarked wilderness.

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My spiritual path, to the extent that I had one, was the trail itself. I regarded long-distance hiking as an earthy, stripped down, American form of walking meditation. The chief virtue of the trail’s confining structure is that it frees the mind up for more contemplative pursuits. The aim of my slapdash trail religion was to move smoothly, to live simply, to draw wisdom from the wild, and to calmly observe the constant flow of phenomena. Needless to say, I mostly failed. Looking back through my journal recently, I found that rather than spending my days in a state of serene observation, much of my time was given over to griping, fantasizing, worrying over logistics, and dreaming of food. Enlightened I was not. But overall I was as happy and healthy as I’d ever been.

Over the course of my first couple of months, my pace gradually increased, from ten miles per day up to fifteen and then twenty. I continued to accelerate as I reached the relatively low-lying ridges of Maryland, Pennsylvania, New Jersey, New York, Connecticut, and Massachusetts. By the time I crossed over into Vermont, I was covering as many as thirty miles a day. In the process, my body was being re-tooled for the task of walking. My stride lengthened. Blisters hardened to calluses. All spare fat, and a fair bit of muscle, was converted into fuel. At any given moment, one or two components of the machine were usually begging for maintenance—a sore ankle, a chafed hip. But on the rare days when everything was running in harmony, hiking a good stretch of trail felt like gunning a supercar down an empty interstate: a perfect marriage of instrument and task.

My mind began to change, subtly, too. A legendary old hiker named Nimblewill Nomad once told me that eighty percent of aspiring Appalachian Trail thru-hikers who give up do so for mental reasons, not physical ones. “They just can’t deal with the daily, the weekly, the monthly challenge of being out there in the quiet,” he said. I begrudgingly learned to embrace the monastic silence of the eastern forests. Some days, after many miles, I would slip into a state of near-perfect mental clarity—serene, crystalline, thought-free. I was, as the Zen sages say, just walking.

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The trail leaves its mark upon its travelers: My legs became a map of black scrapes and leechy pink scars. Ragged holes opened up in my hiking shoes, and beneath those, in my socks, and beneath those, in my feet. My T-shirt began to dissolve from the months of friction and corrosive sweat. If I reached back, I could feel my shoulder blades pushing through the threadbare fabric like budding wings.

At the same time, I began to notice that we hikers likewise alter the trail in our passing. I first recognized our impact when climbing the steep S-shaped turns up hillsides called switchbacks. When a trail is too curvy, descending hikers tend to create shortcuts to skip the turns. I also noticed that in boggy areas, hikers would scramble for dry footing, which split the trail into multiple strands. There seemed to be a basic conflict between the rationale of the trail’s architects and that of its walkers. Later, by volunteering on trail-building crews, I would learn why this is so: hikers typically seek the path of least resistance across the landscape. The trail designers, meanwhile, attempt to build trails that will resist erosion, spare sensitive plant life, and avoid private property lines. (The push to teach hikers “Leave No Trace” principles over the past twenty years has had some success in realigning these divergent value systems.) But even if one assiduously stayed within the trail bed, one would still be altering the trail, because every step a hiker takes is a vote for the continued existence of a trail. If everyone decided to stop hiking the AT forever, it would become overgrown and eventually disappear.

Here is where the notion of the spiritual path, as portrayed in countless holy books, falters: scriptures tend to present the image of an unchanging route to wisdom, handed down from on high. But paths, like religions, are seldom fixed. They continually change—widen or narrow, schism or merge—depending on how, or whether, their followers elect to use them. Both the religious path and the hiking path are, as Taoists say, made in the walking.

Use creates trails. Long-lasting trails, then, must be of use. They persist because they connect one node of desire to another: a lean-to to a freshwater spring, a house to a well, a village to a grove. Because they both express and fulfill the collective desire, they exist as long as the desire does; once the desire fades, they fade too.

In the 1980s, a professor of urban design at the University of Stuttgart named Klaus Humpert began studying a series of dirt footpaths that had sprung up on the campus’s greens, forming shortcuts between paved walkways. He performed an experiment where he erased the campus’s informal footpaths by resodding them with grass. Just as he suspected, new trails soon appeared exactly where the old ones had been.

These impromptu trails, which are surprisingly common, are called “desire lines.” They can be found in the parks of every major city on earth, slicing off the right angles that efficiency deplores. Studying satellite imagery, I have found desire lines even in the capitals of the world’s most repressive countries—in Pyongyang, in Naypyidaw, in Ashgabat. Understandably, dictatorial architects, like actual dictators, despise them. A shortcut is a kind of geographic graffiti, pointing out the authoritarian failure to predict our needs and police our desires. In response, planners sometimes attempt to impede desire lines by force. But this tactic is doomed to failure—hedges will be trampled, signs uprooted, fences felled. Wise designers sculpt with desire, not against it.

Previously, when I found an unmarked trail in the woods or across a city park, I used to wonder about its authorship. But usually, I’ve learned, the answer is that no one person made it. Instead, it emerged. Someone made a stab at a problem, took a tentative trip, and the next person followed, and then another, subtly improving the route along the way.

Trails are not unique in this regard—a similar evolutionary process takes place with other communal creations, like folktales, work songs, jokes, and memes. Upon hearing an old joke, I used to wonder what nameless, forgotten comic genius had written it. But this was a futile question to ask, because most old jokes are not born whole; they evolve over the course of decades. Richard Raskin, a scholar of Jewish humor, has sifted through hundreds of anthologies of Jewish jokes in multiple languages, from as far back as the early nineteenth century to the present, to find the origins of classic jokes. What he discovered was that traditional Jewish jokes evolve along common “pathways”—which usually involve reframing, tweaking logic, swapping out characters and settings, and adding more surprising punch lines—all in search of “a better way of fulfilling the stories’ comic potential.” Like a good trail, a good joke is the result of an untold number of nameless authors and editors. He provides an example from 1928, in which a husband and wife are walking down a dirt road when a heavy rain begins to fall:

“Sarah, pull your skirt up higher. It’s practically dragging in the mud!” cries the husband.

“I can’t do that. My stockings are torn!” replies his wife.

“Why didn’t you put a fresh pair of stockings on?” the husband asks.

“Could I know it was going to rain?”

Raskin deems this joke a failure; it lacks the logical contradiction that lies at the heart of the absurd. But it was a start. Twenty years later, the joke had been tweaked in a number of ways: the setting was moved from an unnamed location to the mythic town of Chelm, which was known to be full of fools; the sentences were sharpened; and the stockings were swapped out for an umbrella, giving the punch line a neater logical paradox. Having passed through countless mouths, the joke had grown from a clunker to a classic:

Two sages of Chelm went out for a walk. One carried an umbrella, the other didn’t. Suddenly, it began to rain.

“Open your umbrella, quick!” suggested the one without an umbrella.

“It won’t help,” answered the other.

“What do you mean, it won’t help? It will protect us from the rain.”

“It’s no use, the umbrella is as full of holes as a sieve.”

“Then why did you take it along in the first place?”

“I didn’t think it would rain!”

+

One torrential afternoon on the AT, as I was hiking around Nuclear Lake, in New York, I turned a corner to discover a black bear waddling down the middle of the trail. It apparently could neither hear nor smell me amid the rain. It went on calmly snuffling along until I clacked my trekking poles together, at which point it spun around, spotted me, and then nervously trundled off into the woods. I stopped to inspect the stubby-fingered, sharp-clawed prints it had left in the mud. Over the following weeks I began to notice other prints—mostly deer, squirrel, raccoon, and, farther north, moose—pressed into the wet trail. When I left the trail to explore the nearby woods, I was surprised to find a shadow kingdom of trails connecting parts unknown.

Humans are neither the earth’s original nor its foremost trailblazers. Compared to our clumsy dirt paths, the trails of ants are downright wizardly. Many species of mammals, it turns out, are also remarkably adept trail-builders. Even the dumbest animals are experts at finding the most efficient route across a landscape. Our languages have grown to reflect this fact: In Japan, desire lines are called kemonomichi, or beast trails. In France, they call them chemin de l’âne, or donkey paths. In Holland, they say Olifantenpad, elephant paths. In America and England, people sometimes dub them “cow paths.”

“We say the cows laid out Boston,” wrote Emerson, in reference to the (probably apocryphal) belief that the city’s crooked grid was the result of paving old cow paths. “Well, there are worse surveyors. Every pedestrian in our pastures has frequent occasion to thank the cows for cutting the best path through the thicket, and over the hills: and travelers and Indians know the value of a buffalo-trail, which is sure to be the easiest possible pass through the ridge.” More than a hundred years later, a study from the University of Oregon has lent credence to Emerson’s claim: forty cattle were pitted against a sophisticated computer program and tasked to find the most efficient path across a field. In the end, the cows outperformed the computer by more than ten percent.

Before colonization, many North American tribes followed deer and bison trails, which found the lowest passes across mountain ranges and the shallowest fords across rivers. Elephants, too, are thought to have cleared the most expedient roads through many parts of India and Africa. Nonhuman animals achieve this efficient design not through superhuman intelligence, but through sheer persistence. They continually search for better routes, and once one is found, they adopt it. In this manner, trail networks of incredible efficiency can arise simply, organically, iteratively, without any forethought necessary.

A clever and patient observer can watch a trail sleeken in real time. The physicist Richard Feynman, for instance, witnessed this phenomenon while studying the ants that infested his home in Pasadena. One afternoon, he took note of a line of ants walking around the rim of his bathtub. Though myrmecology was far from his area of expertise, he was curious to find out why ant trails inevitably “look so straight and nice.” First, he placed a lump of sugar on the far side of the bathtub and waited for hours until an ant found it. Then, as the ant carted a piece of the sugar back to its nest, Feynman picked up a colored pencil and traced the ant’s return path along the bathtub. The resulting trail was “quite wiggly,” full of errors.

Another ant emerged, followed the first ant’s trail, and located the sugar. As it plodded back to the nest, Feynman marked its trail with a different color of pencil. But in its haste to return with its bounty, the second ant repeatedly lost the first ant’s trail, cutting off many of the unnecessary curves: The second line was noticeably straighter than the first. The third line, Feynman noted, was even straighter than the second. He ultimately followed as many as ten ants with his pencils, and, as he’d expected, the last few trails he traced formed a neat line along the bathtub’s edge. “It’s something like sketching,” he observed. “You draw a lousy line at first; then you go over it a few times and it makes a nice line after a while.”

I later learned that this streamlining process extended beyond ants, or even animals. “All things optimize in nature, to some degree,” an entomologist named James Danoff-Burg told me.

Intrigued, I asked him if there was a good book I could read on optimization.

“Sure,” he said. “It’s called The Origin of Species by Charles Darwin.”

Evolution, he explained, is a form of long-term, genetic optimization; the same process of trial and error takes place. And, as Darwin showed, in the great universal act of streamlining, even the errors are essential. If some ants weren’t error-prone, the ant trail would never straighten out. The scouts may be the genius architects who blaze the trails, but any rogue worker can be the one who stumbles upon a shortcut. Everyone optimizes, whether we are pioneering or perpetuating, making rules or breaking them, succeeding or screwing up.

+

After three and a half months I reached the base of Mount Washington in New Hampshire. I climbed it via the Crawford Path, the same trail I had hiked when I was ten. In rapid succession I pieced together a half-dozen peaks that I’d climbed at different times in the past decade: the Presidentials, Old Speck, Sugarloaf, Baldpate, the Bigelows. The order of the mountains sometimes surprised me; it was as if someone had opened my childhood photo album and rearranged my memories. The mountains also seemed smaller than I remembered. Hikes that had taken days when I was a kid now took only hours. It was an eerie sensation—that same uncanny, gargantuan feeling you get from revisiting your old kindergarten.

Any feeling of mastery I harbored was mingled with feelings of humility. I had hiked two thousand miles, but I could never have gotten there on my own. My route had been carved out by scores of volunteer trail-builders and a continuous flow of prior walkers.

I often felt this way on the trail: I was able to hold both one notion and its direct opposite in my mind at the same time. Paths, in their very structure, foster this way of thinking. They blear the divide between wilderness and civilization, leaders and followers, self and other, old and new, natural and artificial. It is fitting that in Mahayana Buddhism, the image of the Middle Path—and not some other metaphor—is used as a symbol of dissolving all dualities. The only binary that ultimately matters to a trail is the one between use and disuse—the continual, communal process of making sense, and the slow entropic process by which it is unmade.

+

On August 15, almost five months to the day after I had started out from Springer Mountain, I reached the summit of Mount Katahdin in Maine. Far below, in every direction, were green forests and blue lakes and islands of green forest within the blue of the lakes. After what felt like months of steady rain, the skies had finally cleared. I could feel the dampness baking from my bones. I had at last reached the trail’s end.

In the center of the peak was an iconic wooden sign announcing the trail’s northern terminus. It had the air of a shrine. Groups of day hikers hung back from it, forming a respectful half-circle, while a handful of thru-hikers approached it, one by one, with looks of reverence and tamped expectation. Each hiker had a moment alone with the sign, posed for a photograph to commemorate the occasion—some exuberant, some somber—and then moved on, allowing the next hiker to approach.

When my turn came, I walked up to the sign, laid my hands on it, and kissed its wind-scoured surface. The moment held a certain surreal quality; I already had imagined it a thousand times. My friends and I popped a bottle of cheap champagne, which we shook and sprayed in fanning arcs into the air. When we finally took a sip, the champagne had already gone flat and warm. That was a rough analog for how it felt to finish the trail: buzzy and yet weirdly dull. After five months, it was over.

And yet, when I moved back to New York City, I found that I continued to look at the world with the eyes of a thru-hiker. After almost half a year spent in mountainous wilderness, the city seemed at once a marvel and a monstrosity. It was hard to imagine a space more thoroughly transformed by human hands. What struck me most, though, was its rigidity: straight lines, right angles, cement roads, concrete walls, steel beams, harsh rules regulated by force. Waste was rampant; everything broke. The trail had taught me that good designs—like age-old tools and classic folktales—are trail-wise: They fulfill a common need by balancing efficiency, flexibility, and durability. They streamline. They self-reinforce. They bend but do not break. So much of our built environment, by comparison, seemed terribly, perilously inelegant.

Meanwhile, everywhere I looked, I noticed new trails: a desire line winding through a tiny park beside the East River, a line of ants inching along my windowsill. I noticed how the shoes of passing commuters wore greasy lines into the concrete of the subway platform, how spots of blackened chewing gum and flattened cigarette butts marked the entrance to nightclubs. Reading omnivorously, I discovered trails running thick through works of literature, history, ecology, biology, psychology, and philosophy. Then I put the books down and walked some more, seeking out fellow travelers—trail-walkers and trail-builders, hunters and herders, entomologists and ichnologists, geologists and geographers, historians and systems theorists—in the hopes of gleaning some common truths from their diverse fields of expertise.

Somewhere along the way I realized that at the heart of my thinking lay a simple idea: A trail sleekens to its end. An explorer finds a worthwhile destination; then every walker who follows that trail makes it a little better. Ant trails, game paths, ancient ways, modern hiking trails—they all continually adapt to the aims of their walkers. Hurried walkers make straighter paths and leisurely walkers make curvier ones, just as some societies seek to maximize profit, while others strive to maximize equality, or military might, or gross national happiness.

The path of a runner often diverges from that of a walker, because, though both may be headed to the same place, they do so with differing priorities. A New Zealand sheep farmer named William Herbert Guthrie-Smith once observed that horse trails in open country will gradually straighten out. However, he noticed that this only took place in areas where the horses were allowed to trot, canter, or gallop. At a slow walk, the horses gladly followed each turn of a sinuous trail, minimizing their work by bending with the contours of the topography. When they sped up, they began to cut the inside corners off the curves, straightening them. If the horses had been allowed to run “at racing speed,” Guthrie-Smith believed they would “in time rule out paths almost perfectly straight.”

The lesson to be found here is not just that the trail of a galloping horse streamlines. It is that both the fast horse and the slow one seek the path of least resistance. When aims differ, trails do too. These overlapping and crisscrossing trails, created by countless living beings pursuing their own ends, form the planet’s warp and woof.

+

This book is the culmination of many years of research and many miles of walking. Throughout, I was fortunate to have been guided by experts in their fields, each illuminating a key element in the long history of trails, spanning from the Precambrian to the postmodern. In the first chapter, we take a close look at the world’s oldest fossil trails, and explore the question of why animals first began to move. The second chapter investigates how insect colonies create trail networks to maximize their collective intelligence. In the third chapter, we follow the trails of four-legged mammals like elephants, sheep, deer, and gazelles, to learn how they manage to navigate immense territories, and how our efforts to hunt, herd, and study them have shaped our development as a species. Chapter four chronicles how ancient human societies stitched together their landscapes with networks of footpaths, which then became tightly interwoven with the vital cultural threads of language, lore, and memory. In the fifth chapter, we unearth the winding origins of the Appalachian Trail, and other modern hiking trails like it, which stretch back centuries to Europeans’ colonization of the Americas. In the sixth and final chapter, we trace the longest hiking trail in the world from Maine to Morocco, and we discuss how trails and technology—having combined to create our modern transportation system and communication network—connect us in previously unimaginable ways.

As a writer and a walker, I am limited by my experience, my background, and my place in history. If this book strikes some readers as too Americentric, or too anthropocentric, I beg their forgiveness; I am, after all, just one American human, doing my best to make sense of a deceptively complex topic. It is also important to note that although the structure of this book is loosely spatial and chronological—moving from the tiny and ancient to the huge and futuristic—this book is not what philosophers call a teleology, a succession of rungs leading up to an ultimate goal. I am not so foolish as to believe that trails have been evolving for hundreds of millions of years only to culminate in the hiking paths of the twenty-first century. I urge readers to avoid interpreting this book’s structure as a ladder leading upward, but to instead regard it as a trail winding from the dim horizon of the past to the wide foreground of our present circumstances. Our history is one of many paths we might have taken, but it was the one we took.

Trails can be found in virtually every part of this vast, strange, mercurial, partly tamed, but still shockingly wild world of ours. Throughout the history of life on Earth, we have created pathways to guide our journeys, transmit messages, refine complexity, and preserve wisdom. At the same time, trails have shaped our bodies, sculpted our landscapes, and transformed our cultures. In the maze of the modern world, the wisdom of trails is as essential as ever, and with the growth of ever-more labyrinthine technological networks, it will only become more so. To deftly navigate this world, we will need to understand how we make trails, and how trails make us.