From the air, I did the inevitable thing, the thing anyone who flies into Roswell must do: I imagined I was looking down from a flying saucer. The outline of the town had surely changed, but the pale gray desert where it's set would have looked more or less the same on July 4, 1947, the approximate date when, depending on whom you believe, either a military surveillance balloon listening for Soviet atomic activity or a spacecraft of extraplanetary origin went down during a violent storm, fireballing to the ground at a ranch 30 miles north of the city. Depending, again, on which source you trust, this mysterious silvery object either did or did not fall to earth so hard that it left a 500-foot scar in its wake, and the resulting twisted wreckage either did or did not contain a number of alien corpses, the number itself being intensely disputed, which may or may not have been taken to the nearby Roswell Army Air Field, flown to Washington, D.C., to be viewed by Dwight Eisenhower, and/or transported, along with the remains of their craft and its potentially recoverable advanced extraplanetary technology, to the secret military installation known as Area 51, in Nevada, where they were autopsied, or not, and/or redeployed in military applications whose potential significance and unimaginable danger to humankind absolutely boggle the mind, or else are total bunk.

Here, then, was the alien's-eye view. A small, whitish cluster – the town – resting on the gray seafloor of the desert, the gray occasionally shading toward brown, the undulations of the landscape marbling into whorls as you looked east, along the Pecos River. It was hard to believe that much had changed since that July 4 (which may have been the exact date; again, there are disputes about the precise order of events, chronologies within chronologies, whole schools of competing conspiracy timelines). It was easy to imagine that you, too, were sailing down from the dark side of the moon.

Just then the spider that lives in my brain twanged a thread, and I remembered a theory I'd seen somewhere, which held that the Roswell aliens weren't extraterrestrials at all, but surgically altered human children. After World War II, the story went, the Soviet premier Joseph Stalin tracked down Josef Mengele, the Nazi doctor-sadist infamous for his experiments on live human subjects at Auschwitz. This would have been in 1946 or so, when Mengele was still living in hiding in Germany. Stalin offered Mengele asylum and his own laboratory if he'd engineer a crew of mutant child-pilots, with their eyes hideously enlarged and adult crania grafted onto their skulls. The idea was that they'd land an aircraft in the United States, where they'd be mistaken for Martians, sowing panic; evidently Stalin had been boning up on his Orson Welles. You can picture the smile frosting Mengele's lips as he heard this. But, the story said, the vessel crashed near Roswell, Stalin went back on his promise, and the fugitive doctor fled ahead of Nazi-hunters to South America, where he died in 1979, at the age of 67, while swimming.

We touched down. Roswell's current civilian airport occupies the same site as the former military airfield; flying into the city, you land at the same place where the alien bodies were taken, if there were bodies, if the bodies were moved. I saw my first Roswell extraterrestrial before the plane had even finished taxiing, a little green tourist-friendly guy peeping out from the welcome sign over the terminal. He was reaching out with his four-fingered left hand to hold up a yellow-and-red Indian sun symbol, which shed its beams into the outline of what I finally realized was the town seal – which, I noticed after another moment, is itself flying-saucer-shaped.

That's how central the UFO crash is to the identity of this place. The wildest conspiracy theory in American history, and they put it on the government letterhead.

At the rental counter the agent looked me up.

"And you're dropping off in … oh, hon, lucky you. Las Vegas!"

"Well, sort of," I said. "I'm dropping the car off in Vegas, but first I'm driving to Area 51."

I figured people must say this sort of thing all the time in Roswell – oh, sure, just casually road-tripping out to America's most sinister top-secret black site – but she looked taken aback. "Area 51," she said, "that's … "

"Yeah," I said.

"You know it's not … "

"It's a thousand miles away," I said. "That's why I'm dropping the car off in Vegas."

"OK, because sometimes people come here and they think – you know – they think it's right next to Roswell, because they hear about them together and whatnot. But Roswell, we're like a tourist attraction, and that's … "

"I know," I said.

"That's not," she finished. She gave me back my ID. "Well, we've got you in a Nissan Sentra."

"I'm driving on Route 66," I told her. "Not the whole way, because you can't, but as much as I can."

"OK," she said. "Well. We've got you in a Nissan Sentra."

I declined insurance. She slid over the gargantuan clove of key fobs.

"Hon, before you go," she said. "Can I ask. Do you mind if I ask why you're doing that?"

It had something to do with the desert and something to do with my brain and something to do with a line I wrote in a notebook once, one of those throwaway thoughts you forget five minutes after you jot them down, except this time I didn't. The line was: "What overwhelms is not the meaninglessness of the universe but the coexistence of an apparent meaninglessness with the astonishing interconnectedness of things."

I flew to Roswell in early spring, the day before Easter. That whole winter I'd been thinking about the desert. Partly this was because of everything that had gone wrong in my own mind. For months, I'd found myself driving too fast and sleeping too little and lying too much, lying almost all the time, really, and mostly to people I loved. I've never been great at communication. Now the gradual disaster of my own choices had left me without even the illusion that I understood myself; I seemed to look out at the world from the other side of a large, bright blank, a space I could navigate only by means of symbols and codes and gestures that made no sense to anyone else. I hurt people I cared about. I cut myself off from the person who best understood me. I was a secret league of one, only with no sense of how to read the directions on whatever inner map was supposed to be my guide to the conspiracy.

There's a word that shows up in old country songs: astray. That was how I felt. Not just lost. Like I'd fallen out of my real life and into some eccentric parallel from which I couldn't find a way back.

All that time, I thought about the desert. I couldn't admit that I was depressed, but I could close my eyes and picture sandstone spires. There is in the image of the desert a nullification that I find almost hypnotic. Think about wagon trains rolling into that immeasurable, unforgiving, all-dwarfing strangeness, the way the tenor of the adventure changes as soon you leave behind rivers and trees for immensities of rock. The orderly progress of the American frontier convulses when it gets to the southwest, because the desert surrounds pragmatic individualism with a silence, a stillness against which it's a speck. A little farther east, your folk heroes are frontiersmen, survivors, builders of cabins and wearers of coonskin caps. In the desert, they're gunmen. They're murderers, or else lawmen who are barely distinguishable from murderers. West of the Alamo, violence takes on a quality of curiously inevitable accident. You always hear it said that Monument Valley is the backdrop for so many John Ford movies because the ruggedness and grandeur of the rocks matched qualities he saw in the young country. I see it differently: To watch John Wayne swagger in front of those wild citadels is to see the drama of American self-definition play out against a backdrop that reveals the utter fragility of the pose, the ongoing inescapable presence of what the pose is meant to keep you safe from. There's a reason the marvels of human engineering we most associate with the desert are some of the most outrageous emblems of [crackly newsreel voice] Man's Conquest of Nature – giant dams, fighter jets, the mushroom cloud. To bring order to the desert requires an ingenuity that is, itself, insane.

Think, too, about how the desert functions in the cultures that border it, how ubiquitously it beckons to hermits and shamans and saints. Whenever a pilgrim needs to reach a holy place, the world has a way of interposing a desert. St. Anthony goes into the Sahara to have visions of men with the heads of hawks and caves teeming with demons. The Huichol in the Sierra Madre travel yearly to high desert mountains, to take peyote and pray. I didn't much believe in ecstatic truth or in my own capacity to receive it. But that winter I would catch myself thinking: What I really want is to get in a car and go west.

And because, in America, the profound weirdness and unknowability of the desert are spiralingly intertwined with the UFO phenomenon, and with the vast network of paranormal experiencers, scientific iconoclasts, hippie mystics, and aviator-wearing conspiracy theorists who populate it, I finally decided to check out some of the marquee sites, poke around a little. I wondered if doing so could quiet some of the tremors in my web.

Downtown, I saw something truly otherworldly. I saw Jesus Christ. He was moving down Main Street, at the head of a small peloton of disciples. I'd dropped my bag at the hotel and gone out to look around, in the Sentra. I saw the Messiah and cruised right past him.

To picture Roswell you have to think of it in layers, one on top of the other, like slide transparencies. The bottom layer looks like a small town in semi-desolation, not an uncommon sight in America these days. On the outskirts, you see horses standing on front lawns. You pass rusted hulks of machinery, looking old in the way the hills do. As you get closer to the center, where the streets fall into a grid, the quality of decline changes, becomes stage-managed. The sidewalks outside the old-timey storefronts sport brick inlays, elegant street lamps. It's only on a second look that you notice hardly anyone is out walking.

Above all this is Roswell's second layer, which floats uneasily over the first. Those dignified old storefronts? They're plastered with little green men. Every other signboard and shop window screams about visitors from beyond the sky. Inflatable aliens sway under the awnings of RV-lite gift emporia with names like Star Child and Roswell Landing. Alien hats for $17, alien shot glasses for $6.50. Wasp-waisted matador aliens posture with capes on the mural outside the Mexican restaurant. The street lamps' frosted orbs have alien eyes stuck on them. At twilight, they look like floating alien heads.

It was twilight now. The light was bluish ash. Jesus and his disciples were moving through all of this, walking south, toward the UFO Museum, and walking slowly, because Jesus was stooped under the weight of the cross, which he carried over one shoulder, Passion-style. Was that a crown of thorns on his forehead? Red blood drenched his white garment, though not his gray athletic shoes. His disciples wore long robes and biblical-looking headscarves. One solitary disciple, a woman in her late twenties or early thirties, had on a sweatsuit. Some of the disciples carried signs. Jesus Loves You. Jesus Died For You. Jesus Saves. Their procession reached an intersection moments before I lost sight of them. I watched Jesus look both ways before crossing the street.

The next morning I stopped in at the museum. The Roswell International UFO Museum and Research Center is a big, dark, warehouselike space with a vibe trapped in the bewildering no-man's-land between "grade-school science fair" and "Kyle, check out my lava-lamp collection." I mean pegboard where you can still see the holes. The exhibits gesture toward neutrality on the question of what really happened the night of the crash; the 6-foot-tall animatronic aliens in the center of the main room are maybe marginally less open to interpretation. They come to life periodically and address the crowd. They sound like Donald Duck impersonating a fax machine into a vocoder. Their flying saucer bloops and spins.

After a couple of minutes I stopped reading the placards and instead eavesdropped on a pair of startlingly beautiful bikers, a man and a woman, neither one possibly more than 25. They were dressed like leather cultists from the future after the fall. Wren's-nest hair, eye black smeared across their cheeks.

"Fuckin' Yodas," the male biker chuckled.

UFOs are an American phenomenon, although they were not, in the beginning, specific to the desert. Or, from another perspective, UFOs are a phenomenon common to every place and time (the pyramids, ever heard of them?) whose characteristics happened to be codified in America, whereupon they entered wider notice. An important early abduction case took place in Brazil; a wave of sightings in France in 1954 led the town of Châteauneuf-du-Pape to outlaw flying saucers, in the interest of protecting the grapes. The so-called foo fighters, mysterious balls of darting-eye light that appeared to pilots on both sides during World War II, were likewise based in Europe. But it was in this country, after the war, that sightings of unexplained aerial lights were first widely correlated with the idea of extraterrestrial ships. At first, the accounts were scattered. A tower reports a flyover at an impossible rate of speed, by a craft it can't identify. Luminous spheres, viewed by dozens, effervesce over a small Midwestern town. A fighter pilot crashes while chasing a gigantic something – but surely the description he called in doesn't make sense? Then people started putting the accounts together, and a narrative began to form.

Apocalypses become quaint the moment they don't happen, which can make it hard to reenter the fear matrix of a previous generation. We know how things turn out, and we have our own nightmares to tend to. Decades of media coverage has turned UFOs into either a tinfoil-hat punch line or an X-Files-ish fantasy-escape. But during the early Cold War years, as subdued hysteria started to set in, the riddle of what exactly all these people were seeing was of mainstream concern. We remember the novelty songs and goofball entertainments playing up the UFO craze — "The Purple People-Eater," say, or Jesse Lee Turner's "The Little Space Girl," from 1959, in which a lonely earthman tries halfheartedly to fend off the advances of an amorous alien in the park. But these were popular because the phenomenon was real. Millions of people took it seriously. Millions of people were, I'm not saying panicking, but at least aware of something sinister in the atmosphere, something not quite right.

It's striking now, when you read the books that helped establish the outlines of the UFO narrative, how hard-bitten they are. My favorite, produced by Donald Keyhoe in 1950, is way more Smoking Man than Mulder; James M. Cain could have written it. It's called The Flying Saucers Are Real. Basically every scene depicts Keyhoe, flinty-eyed investigative journalist, marching into some scientist's lab or government office, overcoat flapping at his ankles, and listen here, buster–ing whoever's inside. I want the truth, see? The truth! The New Age dimension of alien contact hadn't emerged yet, and neither had the idea of a government conspiracy whose byzantine depths made it functionally magical. What you have, instead, is the room tone of an era that had watched the atom split, had lived through the war's devastation, had seen humanity's idea of itself transfigured more than once, in a few short years, and in progressively more breathtaking ways. Why are the aliens here? Keyhoe asks, and the answer is obvious. Because America has the bomb. They're here because of the bomb. The old paradigm was a memory; what could come from the sky put everyone at risk. Why wouldn't aliens show up?

Did you know that Robert Goddard lived in Roswell? Goddard was a rocket scientist whose work paved the way for human spaceflight. Also missile technology. He did, before the war, an intense, tubercular obsessive firing-off of rockets into the desert. You can visit his old lab. He'd been laughed out of the East Coast scientific establishment and had come here to do his work. Work without which, again, there'd be no moon landing, no ICBMs, no rovers on Mars. Goddard thought we could use rockets to reach outer space, spoke of sending messages to alien civilizations inscribed on metal plates. The circularity felt eerie. This was where we'd started the trip to space, and it was where space, or the idea of space, came crashing back down to us.

It was dusk when I found Route 66. Or when I found the ruins of it. It's mostly ruins now because Route 66, probably the most important and certainly the most celebrated component in the history of the American highway system, the road that stitched together Chicago and Los Angeles, making the southwestern desert traversable by car, a road that could plausibly be said to represent the final critical attainment of American westward expansion, the culmination of something that started with Lewis and Clark — Route 66 was decommissioned in 1985, a casualty of the modern interstate. From an infrastructural perspective, this was sensible, even overdue. A skinny, two-lane string wound around mountains and ridges and stretched along canyon rims, 66 was in some ways outmoded before it was even finished. It hadn't been fully paved until 1938, and please pause here to consider the lateness of this date — how, far into the 20th century, well within the lifetimes of many living people, you could not drive across the southwest without venturing onto gravel, onto dirt. Stretches of 66 were so lethally twisty and hairpin-crazed that drivers crossing, say, the Black Mountains in Arizona would hire locals to guide them, like explorers from a different age.

The demise of Route 66, though, also meant the slow bleeding away of the roadside culture that flourished along its edges, a weird medley of midcentury tourist kitsch and car worship (the first fast food was here, the first McDonald's) and pure expressions of the American genius for the deranged carnivalesque. It was slow-moving; that helped. The roadside attractions were right on the side of the road. You just pulled over. There were rattlesnake farms and custard stands, sideshow tents and cases of dinosaur bones. You could see Jesse James's cave hideout and take your picture on the back of a giant jackrabbit. You could stop and tour Meteor Crater, where a meteorite nearly one mile across crashed in the desert 50,000 years ago. The field of appropriated Native American imagery was vast — I mean genres and subgenres of it; in photos, it's haunting. Cabins in the shape of wigwams. Neon headdresses. Arrowheads for sale. Tomahawk-brandishing "chiefs" on billboards for "trading posts."

Visually, this was all bound together in Route 66's cosmic drive-in aesthetic, which is still instantly recognizable today — not just from the eponymous TV show that aired during the '60s (the protagonists wandered from town to town, in the classic guest-star TV formula, solving problems; every season, they started with a new Corvette) but also from its widespread influence. Maybe you've seen Cars, for instance, the Pixar movie, which borrows major elements of both its plot and its look from the history of Route 66. Seen a neon motel sign under the moon, half futurist and half creepy-looking? Seen a filling station with an icebox on one side, a chrome-plated handle on the icebox, a car with big fins under the overhang, and in the background, purple desert? Seen the center line tick past in lonely headlights, cliffs in the distance, a monotony broken only by tumbleweeds? That's Route 66.

It was gone now, or mostly gone. But there were traces, stretches of the old road that were either incorporated into I-40 or accessible via detours, and those were what I wanted to see.

It's extraordinary. I mean, sure, in this day and age we live with our fingertips fused to an archive that holds everything that's ever happened, and one mistyped Reddit search takes you to a streaming clip of the actual Julius Caesar being assassinated, and the results of this are a kind of generalized exposure to historical efflorescence and a radical downgrading of wonder. Still. Ruins are not so common in America that encountering one is ever a familiar experience. Certainly not in the texture-of-daily-life way that you find in other countries — in Italy, say. Even Native American ruins aren't exactly (for obvious reasons) around every corner. As for our late-breaking U.S. culture itself, you sometimes have the sense that we're rolling up the historical carpet behind us as we go, that when we finally vanish, we'll leave behind only garbage dumps and video whose codecs won't play.

"Ruins" might not be the right word, at least not for all of it. There are places along the way where you stand knee-deep in weeds on what used to be the concourse of a gas station, the burned-out retro-sci-fi sign above you slashed with whiskers of rust, nothing else in sight but foggy ridges and, in the far distance, one tiny, moving train: That is a ruin. Elsewhere, the old shrines are still at least semi-inhabited, still eking out some sort of existence. A giant jackrabbit, for instance, can still be ridden, and the curio shop next to it still visited, in Arizona. Across the blacktop lot, there's an ancient yellow billboard, famous in its day, that shows a rabbit silhouette and the words "HERE IT IS" in giant red letters. Surrounding it now: miles of desert, of nothing.

Is that a ruin? No, obviously, because people work there, stop there; when I visited, I found a cash register on the counter and a Mustang parked outside. But somehow the lingering fact of human activity made it seem more lost, not less. The faintness of what was present made what was absent feel so vast.

I'd made a soundtrack for my trip, an infinite-feeling Spotify playlist of '50s hits that I kept streaming at random while I drove. It felt appropriate for the setting, I guess. As I pulled into Albuquerque, "Sleep Walk," by Santo & Johnny, came on. The unnerving quaver of that steel guitar, which keeps bending back on itself, like a snake swimming. It sounds beautiful until you pay attention and then it sounds unbearably strange.

The sun was setting. Cathedral-ceiling clouds. The light reflecting on the city was like disintegrating violet. Central Avenue here is one of the best-preserved stretches of urban Route 66, and there it was, the famous antique neon, the row of historic motels. The Crossroads. The Nob Hill Court. The Monterey, which advertises "luxury rooms" and "European hospitality" for non-smokers. The Westward Ho!, whose sign is a neon cactus. The Premiere, whose sign is the word motel on blue and orange circles, each letter on its own circle, arranged top to bottom: M O T E L.

At my hotel I asked the clerk about the building.

"Oh," she said vaguely, "we reopened a few years ago."

"But the building seems older than that?" I said. It was stone and stately, not at all Route 66–ish.

"Yeah … " She hesitated. "So, OK. It did used to be a mental hospital for children. Before that it was a regular hospital, for railroad workers on the Santa Fe line. Don't worry, we're not haunted! Although we do get, like, written up on those type of websites."

She said the bar was called the Apothecary Lounge. I went upstairs and unpacked.

I thought about the war. This isn't much remembered now, or much talked about, but there were POW camps throughout the United States, holding hundreds of thousands of prisoners. There'd been one near Roswell. Five thousand German soldiers. Most were captured from among Rommel's forces in North Africa. They were put to work on local ranches and farms — and try to picture that, if you can, hundreds of troops from the Nazi Afrikakorps picking cotton in the New Mexico desert.

In 1943, a small detachment from this group, 50 or so men, had been assigned to pave a section of the Spring River, which runs right through town, lining the sides of the channel with large stones. Working in secret, the prisoners managed to construct a mosaic, which they embedded in the riverbank. It's a crude but unmistakable depiction of the Iron Cross.

When the townspeople discovered what the soldiers had done, they were furious. The second-most recognizable symbol of the Wehrmacht right there in the middle of Roswell — unthinkable. They buried it under concrete. Over the years, though, the concrete washed away. The town had a dilemma, because on the one hand, the mosaic was history, a remnant from a time that deserved to be remembered. On the other hand, Nazi symbolism, even of the ad hoc and vaguely pitiful sort that Roswell found on its riverbank, is tricky to memorialize. Do it wrong and you're inviting Aryan Brotherhood pilgrims in by the Silverado-load.

Roswell did it exactly right. They built a small park across from the Germans' mosaic, dedicated to the world's prisoners of war and to soldiers missing in action. They put a display case up, holding a piece of the Berlin Wall. There's a historic marker, which tells the story of the POW camp, and a viewing platform. There's a little basketball court, which looks out at the Iron Cross.

Not long before I left town, I'd stopped at the park, stood by the marker, and looked out across the river. There was the cross, at the center of a ring of pale stones. It felt less like an emblem of enmity than like a residue of ghosts. What had things been like, here, when the war ended? Five thousand people, even enemy soldiers, can't disappear from a place this small without leaving some kind of void. Even if their imprisonment kept them separate, even if their going meant the return of the local kids who'd been serving abroad. They'd been part of the landscape. In the fields, on buses, with their guards. You'd catch glimpses of them around the county, and undoubtedly happenstance had produced moments of unexpected interaction, conversation, memories that meant who knows what. Then, just — gone. How do you process something like that? As a culture, I mean, or just as a human being?

Why was I going to Area 51? You can't exactly show up and take a tour. Area 51 was no longer secret — that is, its existence wasn't, having been formally acknowledged by the CIA in 2013; before that, it was officially a non-place, occupied but unconfessed, somehow real but also not — but whatever went on there was hidden in top-secret midnight. To find out, you'd need a level of security clearance it took security clearance just to know about. And it isn't as if the site itself is accessible. Geographically, Area 51 is part of the Nellis Air Force Base Complex, the New England–state-size military training and testing Xanadu in the remote desert northwest of Las Vegas, but it operates on its own, via protocols of impenetrable ghostliness. The internet, where, like the stop-at-nothing Keyhoe-esque investigative reporter I am, I had done most of my research, spoke of unmarked backcountry roads, of navigating via baleful-sounding landmarks ("the black mailbox"). Of unmarked white pickup trucks that sat on high hills, watching. The front gate, near the minuscule town of Rachel, Nevada, wasn't even a gate. I mean, it didn't close, was what I'd heard — there was just a warning sign in the middle of what was otherwise fathomless emptiness.

Your wisest course of action, the internet felt, was not to cross that warning sign.

"Area 51" was probably not even Area 51's real name. We don't even know where it came from. It first shows up in a declassified CIA document from 1967, where three "Oxcart" planes — a codename for the Lockheed A-12 high-altitude reconnaissance aircraft — are said to be deploying "from Area 51 to Kadena" for surveillance of North Vietnam. Beyond that, the name's origin disappears into a tangle of competing theories. The area has been a locus for UFO sightings since the 1950s, when Project Aquatone, the U-2 spy plane program, started sending very high-altitude aircraft over the Nevada desert under conditions of extreme secrecy. Those were UFOs in the technical sense, unidentified objects that flew. But Area 51 only entered general notice in 1989, when a man named Bob Lazar gave an interview on Las Vegas TV in which he claimed to have worked there, reverse-engineering alien spacecraft. He described underground hangars, elements not on the periodic table, alien entanglements in human history going back 10,000 years. Lazar's story was torn to shreds by critics; it turned out he'd possibly lied about his education (MIT) and background, and there were plenty of reasons to think he was making the whole thing up – but other details checked out. So there was a controversy, which put Area 51 on the map and, in the same motion, took it off of it.

I'd seen Lazar in person that winter, at the International UFO Congress near Scottsdale, where, after a show of reluctance, he'd agreed to give a Q&A and end what he portrayed as his self-protective withdrawal from the UFO community, which he blamed for ruining his life. To me he seemed weary more than anything. Weary from problems of his own making or because the government really had gone after him, who knows. He was busted in 1990 for abetting a prostitution ring; maybe that discredited him, or maybe that was exactly what the men in black would do to discredit him. Who could say?

Lazar called the site where he said he'd worked "S4." The CIA was known to use the term "Groom Lake," but that was merely the name of the nearby salt flats. People who worked at the facility were said to call it "Dreamland."

But none of these names told you much. It was as if the jigsaw puzzle of the American West had had a piece pulled out, and the resulting blank space, a nowhere enclosed within somewheres, became Area 51. The fascination it exerted, as the vanishing center of every rumored cover-up and labyrinthine conspiracy theory, was essentially the fascination of a vacancy.

I said before that the UFO phenomenon was not limited to the desert, and that's true; the first widely reported abduction happened in New Hampshire, and sightings and reports of alien contact occur regularly all over the world. Still, the desert is essential, and not just because the air force bases put a lot of lights in the air. It's because the desert is where the stories themselves seem to gravitate. The myths drift there, inexorably. It's where they most make sense. The desert holds Area 51 the way Area 51 holds its secret spacecraft — it encloses something improbable within an impossibility that makes you think it could be real.

I drove west, streaming oldies. Albuquerque toward Flagstaff. I guess I'll never see the light, I get the blues most every night. There are places in central New Mexico where the plateaus look like lavender shadows from a distance, like something in a Chinese ink painting. Then you get close and see the rusts and bronzes in the rock, reddish-brown blotches like liver spots. Guardian angels up above, please take care of the one I love. I stopped at the mining museum in Grants, once known as the uranium capital of the world, and rode the elevator down to the mine floor, where every station plays a clip of a miner describing his work. The atom bomb was created in New Mexico, and then, only afterward, only in 1950, massive concentrations of uranium were discovered there. Time goes by so slowly. Across the street stood one of the classic surviving Route 66 signs, an unlit wreck of green neon: Uranium Cafe. And time can do so much.

I spoke to a man who said owls forecast his destiny. We didn't speak in person — we talked on the phone. People who've experienced what are called "high strange" paranormal events, including alien abduction, are often understandably reluctant to get close to reporters, whom they've learned to regard with wariness. Say you've been on a spaceship, or that you've experienced any of the stereotypical abduction events, and here's what will happen. First, the media will approach you with an outward show of understanding. Then, once you've signed the release forms, the media will paint you as a raving crackpot. Tell me, sir, were you probed? Mike wasn't shy, though. He's a people person, a wilderness guide in the mountains, where he lives. He just wanted to feel me out before he put me in touch with other experiencers. ("Experiencers" is the preferred term here, since "abductee" doesn't apply to people who've gone with aliens of their own free will, and "contactee" has positive-sounding connotations that actual abductees don't like.) On the day I spoke to him he said I'd caught him "well caffeinated," and it was true that the sentences tumbled out of him. He'd bring up Jung's theory of synchronicity and then describe his "mission in life" and then talk about "vocabulary words," as in, "I don't have the right vocabulary word for what happened next."

He'd encountered so much strangeness. Not just the owls, although owls haunted his memories, but also floating orbs, glowing beings, missing time, coincidences for which the only possible explanations flirted with magic. He'd been brought onto alien ships. He'd woken in the night to find himself floating in the air. There's video on the internet of Mike speaking to UFO groups, something he does a fair amount of, and you have to pay close attention because he jumps so fast from one thing to the next: Now we're having a vision of a terrifying face, now we're in a sweat lodge with a shaman. There's a beauty to his stories, though, most of which are about how, when something truly inexplicable happens, owls tend to turn up around the edges of the event. You'll see a dozen of them on a telephone wire, and then, around the next corner, the spacecraft. Mike's written a book, collecting accounts of owls as harbingers. He thinks they might be psychic projections of extraterrestrial beings. As in, cloaks that aliens wear. He describes lying in the woods, feeling the silent passage of their wings.

He's not crazy, that's the thing. I mean, much of what he says is beyond incredible, but you never doubt that there's a reliable, if slightly high-key, consciousness on the other end. You'd trust him to get you back out of the forest. The same held for most of the UFO experiencers I met in the weeks before I flew to Roswell. Yes, some of them seemed nuts, and some of them were lying, and some of them were probably both, but the bulk of them? The bulk of them seemed sane. Fragile and shy and scared of attention, some of them, sure, just as you might be if you'd been through something that ripped open your sense of reality. And the same could be said for the ones with an exaggerated sense of self-importance, of grand mission – you might think you were important, too, if you were bringing news of cosmic significance. But neither timidity nor grandiosity mean that you aren't telling the truth.

And they weren't being consciously untruthful. I mean, I'm speaking only about my own reactions here. Maybe I'm easily misled. Regardless, my inner alarms, most of the time, did not start ringing. There are psychological studies that bear this out. People who say they've been abducted by aliens tend to show PTSD-like symptoms when they're pressed on the topic of alien abduction; otherwise, they're not appreciably mentally ill, or not more so than the rest of us. They pay taxes and watch Hulu and decide which toothpaste to use, and then just happen to live with this one deep sinkhole of terror. (Or of wonder; I don't know the ratios here, but there's at least a noticeable minority of experiencers who feel they've been chosen, not singled out for torment.) But not trusting their honesty because they seem "strange" makes no sense, because being lifted into the sky by extraplanetary beings would of course have that effect on "normal" people. This is one of the logical reversals you tend to fall into around UFO people. It's like saying "Oh, Jake is really on edge — he must be lying about what happened in the war."

What I'm saying is that there's a legitimate mystery here, which is: Why do so many people say, and seem to believe, that they have had experiences that cannot, according to any plausible reading of reality, have happened? Stats are hard to come by for obvious reasons, but the number of people who say they've been abducted runs at least to many thousands. And yet no indisputable photographic evidence, in an era when nearly everyone carries a camera? No multiple-eyewitness accounts that aren't at least somewhat slippery? Nothing undismissable picked up by, say, news satellites, by Google Earth? At a moment when it sometimes seems the planet is encased in a shell of surveillance? In a sense, the conspiracy-theory aspect of the UFO phenomenon, the but that's just what they'd want you to think! side of it, was inevitable, because something had to reconcile the certainty of experiencers with the lack of ironclad evidence — and the only way to do that is to turn the lack of evidence into its own kind of negative proof.

Here UFO believers will stop me to insist that there is evidence, mountains of it, and they're right. There are countless reports of lights materializing over cities, of group-abductees who forgot the event, then went under hypnosis and recovered identical memories. There are countless photographs, of various degrees of graininess. The government really did take flying saucers seriously. There was an Air Force initiative, Project Blue Book, that tracked reports, and this wasn't because postwar American intelligence was so silly but because once you are tasked with actually mapping the line that separates folklore from reality, you discover that the border is maddeningly blurred. But all this evidence has an odd sort of vanishing-around-the-edges quality. It's confirming to people who are already inclined to believe and unpersuasive to people who aren't. So much of it is on the order of "children in a small town all started drawing the same picture of a gray man with dark eyes." Which is haunting, compelling, but not quite the same as "an ocean liner appeared in the sky over Times Square."

The problem this creates is analogous to the problem of religious experience; it's fascinating and disturbing in the same way. What do you do when someone whose word you have no reason to doubt claims to have seen God? When you yourself haven't? Your sense of reality either expands around that possibility or it doesn't. A big difference between religious faith and belief that aliens walk among us, of course, is that God is often thought to occupy what we might crudely call a higher order of reality, while aliens presumably exist within ours. (Another difference is that the experience of religious visitation leaves most people overjoyed; you don't get a lot of PTSD from it, although it blows your perceptions wide open.) Still, the abduction narrative has many features in common with, say, the writings of mystic saints — the blinding light overhead, the sense of telepathic communion, the slow floating upward. You don't have to look hard for theories that the "angels" described by ancient writers were actually beings from space (or, on the other hand, that the aliens described by experiencers are the atomic-age equivalent of fairies).

Paranoia is skepticism taken to the point where it becomes faith. In the same way, the alien trope takes 20th-century scientism to the point where it becomes mystical. Which has nothing to do with whether people have actually experienced it. Remember how I said that Area 51 was both there and not there at the same time? Spend enough time with these questions and you end up feeling like Augustine, who wrote of God and heavenly creatures that "they neither are nor are not in existence."

Or almost. Looking back at that quote, I realize I have it backward. It's God, in Augustine's formulation, who is entirely in existence. (Of course it is.) It's what isn't God — our world, our rooms, our memories, our faces — that both is there and also is not. What's real and also not? A dream, right? Augustine isn't saying that God is like a dream we're having. He's saying the opposite. He's saying we're the dream, not the dreamer. He's talking about us.

In western New Mexico, on the edge of the Zuni Mountains, there's a place called Inscription Rock. I drove miles out of my way to see it. It's a sandstone cliff rising out of the desert. Bleached-looking bluffs. A kind of rough-hewn natural fortress, towering 200 feet over low tangles of juniper and ponderosa pine. The conquistadors called it El Morro: the promontory. Walk around the base and you find a fold in the cliff that makes a small, shaded grotto, where rainwater gathers in a pool. Just rainwater — there's no underground spring or anything like that.

For hundreds of years, if you wanted to cross this desert and survive, this pool was your best hope. Going back to the Spanish, even before. Even a long time before. The little rain basin at El Morro was the vital link for generation upon generation of travelers.

The oldest carvings on the rock are ancient petroglyphs, made by native Puebloans around 1,000 years ago. Handprints. Bighorn sheep. Human forms with box-shaped torsos. Over the centuries, as the land was colonized by successive waves of explorers and then missionaries and soldiers and settlers, a sort of ad hoc traveler's custom arose whereby anyone passing through would etch their own names into the stone. Not like a formal tradition. Just, one person did it and then the next person saw that inscription and copied it. Many of them wrote a little bit about their journeys. The first message from a European was carved in 1605. That's 15 years before the Mayflower landed.

There are 2,000 carvings. Some are crudely scraped, some chiseled with a finesse that's nearly calligraphic. The oldest belong to Spaniards, whose messages are small windows onto the moment when breastplated and shiny-helmeted conquistadors ventured into what they saw as this untamed desert vastness. Paso por aqi el adelantado Don Ju de Oñate del descubrimyento de la mar del sur a 16 de Abril de 1605. Governor Don Juan de Oñate passed through here after the discovery of the Sea of the South on the 16th of April of 1605. The Sea of the South — that's the Pacific Ocean. Oñate didn't discover it for Spain (Balboa had done that); he was looking for an outlet. They knew it was there, but not how to find it. This was the era of lost cities of gold, of Terra Australis. The map of the world was still full of blanks. To survive on the way back to New Mexico, Oñate's men had to eat their horses.

So right away, as you stroll the path beside the cliff's base, you're looking back in time. At crueler histories, too: Oñate's brutality to the Native Americans he encountered was so extreme that he was eventually put on trial for it, not an easy achievement for a colonial governor in Nuevo México. He "dealt harshly" with "rebellious" Indians, is how old history books put it. Newer ones say that he cut off the feet of captives from tribes he wanted to subdue. (His real crime, in the eyes of the king, was probably running out of money.) Another inscription, from 1632, tells of the passing of a group of soldiers on their way to "avenge the death of Father Letrado," a missionary who'd been killed and scalped by the Zuni. In 1680, the Pueblo rose up against Spanish oppression and drove out the colonists; 12 years later, Diego de Vargas arrived with a military force and reconquered Santa Fe. "Here was the General Don Diego de Vargas, who conquered for our Holy Faith and for the Royal Crown all of New Mexico at his own expense, year of 1692," his carved inscription reads. At his own expense — what a glimpse of character in that one tiny flourish.

The Indian Wars are written all over this place. Cavalrymen sent by the U.S. government to secure the southwest passed through before the Civil War. When he was secretary of war for the United States, Jefferson Davis had caused the formation of an experimental camel corps, had sent dozens of camels with American troops into the desert to see if they'd haul supplies better than mules; one of these contingents passed through here in 1857. P. Gilmer Breckinridge, who oversaw 25 camels, signed his name. The next year saw settlers bound for California. One member of the group to leave an inscription was 12-year-old Sallie Fox, traveling west with her family. After they moved on from the rock, Mojave Indians attacked the wagon train. Sallie was shot through the ribcage with an arrow. She endured the long desert trek, mostly on foot and with a high fever, back to Albuquerque with the survivors from her party. The dress she was wearing is now in the historical museum in Vacaville, California. There's a little rent in the right side of the chest, where the arrow went through.

Among the inscriptions, there are countless hidden stories, countless mysteries. That Oñate message, for instance — did he carve it over a petroglyph, expressing his contempt for the Indians? Or did the Pueblo carve the image, a human figure, over his words, expressing defiance against a sadistic enemy? It would be fascinating to know, but we won't know, because it's difficult to date the glyphs, and also because the inscriptions themselves are vanishing. The sandstone is so soft. That's what made the graffiti possible in the first place; it also means that every day, the wind carries away a little more. Already many of the inscriptions are hard to read. The Park Service is trying to preserve them, but at best, the erosion can only be slowed.

A park ranger warned me that it was "breezy," but I wanted to see the top, so I followed the thin track up along the promontory's side and then stepped out onto the rock. The wind was cold. There were places where twisted low pines grew out from between cracks in the sandstone. Erosion had left weird, cowboy-dimension shapes in the summit's profile. Shattered-looking steeples. Long protuberances that called to mind strange masks. The gusts were hard enough at times that I had to hunch down to keep my balance. To my left, the cliff's edge fell away, and the view spread out for miles, pale flat valley floor studded with dark knots of trees. At the horizon, a low ridge lay along the sky like a sea monster's surfacing back.

Make your way far enough out onto the bluff and you come to a ruin. There was a village here, established more than 700 years ago by Ancestral Puebloans. (It's no longer seen as acceptable to call them by the pejorative term the Navajo used for them, Anasazi, meaning "ancient enemies" or "ancient strangers.") Little is known about them. They were responsible for many of the petroglyphs; Zuni Indians who found the site much later called it Atsinna, or "place of writings on the rock." Not much of the village remains: a small grid of recessed stone walls, a larger room that may have been used for religious ceremonies.

The civilization of the people who built this place leaves a baffling trail in the historic record. If you look at the evidence from a certain angle, they seem, all of a sudden, to disappear. This would have happened centuries before even the Spanish arrived. For many years, what became of them was a great unanswered question in American archaeology. It's now generally accepted that they migrated to the southwest, to areas with more reliable sources of water, where they merged with other Puebloan cultures. Which makes sense. Still, there's an air of mystery around them, and standing on the rock by the ruins of their pueblo, I couldn't help remembering a theory I'd heard repeatedly from UFO aficionados. The theory said that they vanished because they were taken away by aliens, or else because they were aliens — ancient strangers, traveling some long-forgotten road back to the stars.

I drove for two more days. If I could take you up in paradise up above. West through Arizona, then north, into Nevada. The Black Canyon looked like nothing I'd seen in this world. If you had to dream up a lost kingdom for a fantasy novel, that's the sort of landscape you might invent. I spent a night in a Navajo casino. The next night I spent in Las Vegas, where I walked around for hours, until the colors started to carousel. Life could be a dream, sweetheart.

To get to Area 51 from Las Vegas, you take US 93 north for 90 or so miles, then exit onto Nevada State Route 375, the so-called Extraterrestrial Highway — the state renamed it in 1996, during promotion for Independence Day — and follow that for an hour into increasingly remote desert. You're driving along the northern edge of Nellis Air Force Base, part of that vast reserve of military land, but there's no indication of that, no signage, hardly any other traffic. Eventually you get close to Rachel, population approximately 50, where there's an alien-themed motel (the Little A'Le'Inn) and not much else. An X-Files episode was set there. I had lunch at the motel, in a greasy spoon full of alien-themed bric-a-brac. No one else was in the place except a couple of Australians, one of whom was very drunk and wearing a tinfoil Viking helmet he'd apparently made himself. It had little tinfoil horns on it. He kept shouting about how "radical" everything here was. The woman behind the counter was sighing as she smooshed my burger patty down on the griddle.

The roads get smaller as you close in. First you're on a highway, then you're on gravel. Then dirt. The desert here is riddled with Joshua trees. Have you seen them? You've heard about them, anyway — twisted, long-limbed evergreens that put Mormon settlers in mind of the prophet Joshua, arms flung up in prayer. This is, incongruously, free-range cattle country — everyone rushed to warn me about that, local people I mean, when I said I was going to Area 51; nothing at all about men in black, but be careful, the bulls will charge your car — and every few hundred yards there'd be a little clutch of them, lying in the brush under the Joshua trees. Like they'd built nests.

The song that came on, as I drove among the cow-nests and the twisted trees, was "Maybe" by The Chantels. So I drove for a while and listened to that. Maybe if I pray every night, you'll come back to me. I passed the skeleton of a horse, lying on its side in the sand. Maybe if I hold your hand, you will understand. I don't think I've ever felt, in the continental USA, so far away from everything.

Then "Maybe" ended, and "Papa Loves Mambo" came on. I wish, for the sake of atmosphere, that I could report otherwise, but it was "Papa Loves Mambo" that was playing as I came into view of Area 51.

There were tourists at the gate. A minivan full of them. In retrospect, that seems inevitable, but at the time, I think it was the most surprising thing I possibly could have seen. They'd gotten out and were snapping away with their phones. I stopped the Sentra 30 yards or so behind them, so taken aback that it took me a minute to realize that what I'd read on the internet was true. A ways back from the gate, there was a sort of rise in the landscape, not quite a hill but a high enough undulation to give a view of the immediate surroundings. A white truck was parked up there. It didn't move, didn't offer an inkling of life. Just sat there, looking sinister. Mama loves mambo.

I keep saying "gate," but there wasn't a gate. Just two warning signs, one on either side of the road, nothing to keep you from driving right past them. Except that the signs say, in crisp military English, Entry is unlawful without written permission from etc. Abandon hope, all ye who enter here. The tourists went right up to the signs to take selfies but did not, I noticed, step beyond them.

The whole thing seemed vaguely ridiculous. But then, dreams often are. Here I was on the threshold of Dreamland. Anyway, what could I do? I'd come here. Now I was here. The minivan drove away and I pulled forward. Beyond the signs, there was nothing. More desert. I walked up to the line and looked over. After days of strange profusion, it was almost a relief to see something so inaccessible to knowledge, such a complete refusal to be anything but an absence. The thought I had was that I had finally reached the frontier, that when we ran out of west in America we locked the idea of it away in places like this, blanks on the map that could never be charted, where who knew what monsters might exist. And sure, I thought about flying saucers. But mostly I thought about nothing, about the not-answer that lay beneath even my ability to ask questions. I remembered the sign I'd seen: Here it is. And how hundreds of miles away and in a different desert, what was left of Route 66 still ran westward, from Arizona into California and across the Mojave to Los Angeles, to the place where it ended at the Santa Monica Pier, by the Ferris wheel on the edge of the sea.

There was one more place I needed to visit. A few months after my road trip, I sent an email to the Army, asking for permission to visit the Trinity site. They said yes. Don't ask me why. It's where the first atomic bomb was detonated. Typically, the site is open to visitors two days a year, in April and October, that's it, and I'd missed both days — but the liaison, Ednamaya (she went by Lisa), took pity on me and agreed to drive me out. Also I got lucky, because it turned out that an undersecretary of state was visiting on the same day, and Lisa was willing to ferry me around after she'd finished the official excursion.

Trinity is 100 miles or so south of Route 66. It's inside the White Sands Missile Range in southern New Mexico. Another gargantuan expanse of military land, 3,200 square miles, so huge that driving across it kills a workday. It's mostly empty terrain. On the drive out to Trinity, I noticed that some of the base's road signs showed silhouettes of animals I didn't recognize, black shapes inside yellow diamonds, horselike heads with long, spiral-turned, gently arcing horns. Lisa told me that in the 1960s, the base commanders had imported "2,500 oryx from the Kalahari" in order to stage exotic game hunts. Since the oryx's major predator was the lion, and since, as Lisa pointed out, "we don't get too many lions in New Mexico," the herd had thrived such that there was now a basically self-supporting population of wild African antelopes contained entirely within the American military apparatus's largest missile-test zone. No distance at all from the spot where the atomic age was born.

On the drive back, I saw them. Beautiful creatures. Like stout horses, but with startling black-and-white facemasks and the tall V of the horns, which seemed to belong to different animals entirely, more ethereal but also more demonic. The herd was set back from the road, just grazing. There were many oryx. I was in a distracted state from having seen Trinity and from having stood, alone except for Lisa, on the spot where, on the morning of July 16, 1945, the first mushroom cloud had risen over the desert, an explosion of such ungodly power it shattered windows 150 miles away. The ground there still glitters with green rocks called trinitite, created when quantities of sand from beneath the bomb tower were sucked up into the blast, vaporized, and left to re-form into a radioactive substance scientists still don't fully understand. Green flakes of it appear around the many small holes that dot the site. I'd wondered if the holes were related to the bomb, but Lisa said no, they were rabbit holes — there are rabbit warrens running all beneath ground zero.

So when I saw the oryx, I was not, mentally, all the way online. What I was thinking about was a poem by John Donne. It's the poem that Robert Oppenheimer, who ran the Manhattan Project, cited when asked why he'd chosen the name "Trinity" for his nuclear test site, even though (as Oppenheimer himself noted) the poem has nothing to do with the Trinity. It's a poem about traveling west. "Hymn to God, My God, in My Sickness" finds Donne on what he believes to be his deathbed, lying surrounded by doctors, and because it's the early 17th century, Donne starts imagining the doctors as "cosmographers" and himself as a map, the sort of map an explorer might make, filling in the world's blanks.

Whilst my physicians by their love are grown
Cosmographers, and I their map, who lie
Flat on this bed, that by them may be shown
That this is my south-west discovery,
Per fretum febris, by these straits to die

Per fretum febris: by the wasting away of a fever. That was Ferdinand Magellan's cause of death, when he died while trying to sail around the Earth. (He really died while trying to convert the Philippines to Christianity by force, but that was a subcomponent of the larger expedition.) Magellan had discovered the strait that made passage between the Atlantic and the Pacific possible; Donne is reimagining this as the passage between life and death. To go west is to die, and yet —

I joy, that in these straits I see my west;
For, though their currents yield return to none,
What shall my west hurt me? As west and east
In all flat maps (and I am one) are one,
So death doth touch the resurrection.

Travel far enough west, on a map, and you come out on the other side, in the east. In the same way, Donne says, if you travel into death, you emerge into resurrection. History's unreturnable current moves one way, but creation is a sphere, not a plane, so nothing is really final, nothing is lost. What shall my west hurt me?

I was not in my right mind. But I was thinking please, let me believe it. Then I saw the oryx. They made no sense there. They made the opposite of sense. This isn't a generic desert landscape. You would recognize these ridges, these grasses, this light as New Mexico in a photo from the moon. In the same way, the oryx are unmistakably from where they're from. The image didn't fit.

And yet. Let me believe it, I thought. What I want to say is that for a minute, maybe two, after I saw them, I almost did.

The road out of Trinity ran perfectly straight, as far as I could see.