Everyone warned me not to take the route along the Gulf, in the northeast corner of Mexico, through the state of Tamaulipas. The mass graves discovered outside the town of San Fernando last year contained close to 200 bodies—the victims kidnapped from passenger buses, migrants caught in the crosshairs of the internecine narco war. In town after town just south of the border with Texas, men are found dead in shallow graves and women are wearing the guns and badges of police.

I run an English used bookstore in Mexico City (a beautiful and, for the time being, very safe place, nothing like what most Americans think) and had some books sent by my most generous patron in Seattle to pick up in Austin because I couldn't trust them to the mails. Friends said take the long way: Drive up the Altiplano—where the high, vast, tilted plain acts like a giant satellite dish, and you hear radio stations in Alaska—to Nuevo Laredo and cross the border there. But it seemed the straightest, cheapest route was to cut east four hours into the state of Veracruz and follow the coast north.

All the travel books and websites and unsolicited advice and insurance policies say not to drive at night in Mexico. The free roads are—to put it gently—unreliable: signage poorly placed, potholes deep and wide, road striping occasional, streetlights even more rare. It's not quite a dangerous free-for-all, but it's more work than driving in the US, because it's a realm pretty much without rules: You have to pay close attention, but everybody else is doing the same. I think the super-evident death toll of driving in Mexico (each deadly accident commemorated with a shrine) is probably more due to poverty (bad roads, sleepy truckers, cars seat-belt-less and crammed full of people) than recklessness. In the US and Canada, to drive feels like entering a vast machine: parts labeled and brightly lit, road smooth, green means go and red means stop. You can practically do it in your sleep—or, having overslept, shave, read the paper, talk on the phone, eat, drink, sing to the radio, etc. As wild as driving in Mexico sometimes gets, you'll very rarely see anyone on the highway do anything but watch out.

So driving only in daylight, it looked like four short bursts between safe havens of RV parks or hotels in four towns before the Rio Grande. These RV parks existed (or seemed to, on the internet), which meant people used them on a daily basis, thousands a month, you'd have to assume, right? I repeated this vague calculation like a mantra. I thought this route would be cheap, I wanted to swim (at beaches that turned out to be bunk), and I'd already found a rider on Craigslist to split gas. The van was a worn 1995 Econoline, its greatest liability not mechanical but its Washington plates, which made it an immediate target for police shakedowns. My friend Lina, a child of Mexican parents raised in the US, said to make myself and my passenger as filthy and incomprehensible as possible: Don't bathe, scatter the van's interior with food and waste the cops won't want to touch, affix punk bumper stickers to the back.

How empty the highways were of people like us I had no idea. But I felt like we could ask along the way for a real picture of what we were going into, and if it sounded too gnarly, surrender and head inland. But people, Mexicans—a couple of whom I didn't even think liked me—kept urging me not to go through Tamaulipas. Was something tantamount to a civil war, they said, not enough? Wasn't a van piloted by two honkies (one looking like a Boston Irish cop and the other like his Hollywood-hippie rookie partner) enough to attract at least a look from every single person seeing it in four states, at least some of whom would have intentions less than amigable? Was I totally crazy? Similar bogeymen floated over Tijuana, Sinaloa, and Michoacán, until I drove through those places myself and found life proceeding peacefully and everyday. Tijuana was said to be crawling with death, and yet when I walked across that town at midnight two years ago with nothing but my backpack, I was fine, carefree as crossing a supermarket lot in Seattle. Same with traversing the traficante-infested city of Tepic on New Year's Eve entirely without incident, after which I heard Tepic was deadly: stacks of heads found on a daily basis, a curfew at dark (that no one paid attention to), etc. Let me be clearer: The narco murders—tens of thousands, at least—are real. Bloody business goes on in the articulated shadows of daylight, as it does all over the hemisphere. But people in Tijuana and Tepic did not seem in the least either frightening or afraid.

Simon, the 25-year-old Canadian who answered my Craigslist ad, had been all over Mexico in the last year—and before that China, Australia, East Timor, and Indonesia—and knew how rarely the horrific legends you hear were borne out. I showed him two discussion boards in which hysterical rumors were shut down, one by a traveler who had actually driven the Tamaulipas coast and another who did so regularly.

But Tamaulipas and Nuevo León aren't even in the big guidebooks, as if they don't exist. I've thought ever since emerging from my adolescence—strangely cloistered despite its globetrotting reach, in front of the same bright box that raised us all, with so many wrong ideas about how life goes on—that our familiar phantoms are unreal. TV and movies are our mass dreaming, and something as mundane as poor job satisfaction or ordinary sexual frustration can find its vent in the arithromania of a police procedural or the image of a splash of blood on black. I was 8 years old on a navy base in Spain the summer I learned about The Texas Chain Saw Massacre from other kids at the pool. None of us had seen it, but we accepted it as documentary fact, the way kids will into being that perceived half-reality we maybe never quite grow to understand is entirely false. Just the aura surrounding the film made me so uneasy, I didn't watch it for 30 years. It is a shadow play of wicked impulses and a masterpiece about the helpless inevitability of economic entrapment—what you might find if you run out of gas.

Forty years ago, the Manson gang picked a house—apparently at random—in Benedict Canyon at which to invite nightmares to play in the sun ("I am the devil," said the tall all-American Tex Watson to one victim, "and I'm here to do the devil's work"), and the crimes of that night are like a bell that has shaken every atom of our time. Somewhere between the noir that assured suburban America the cities they abandoned were a cesspit and the TV news demonization of the young black male as a type, Americans came to see the stranger as enemy, the worst thing imaginable likely true. When I started living in cities, I came to feel I'd been under a common delusion: The mass nightmare had prejudiced us against the day itself. I saw that we were all, to some extent, hallucinating together, and the world is consistently a gentler place than we believe, waiting for our hearts to open.

Tuxpan had the half-abandoned air of a navy town, which it was. On the beach, a seafood restaurant appeared to be open, and we pulled in, the apparent customers in fact hosts. We ordered dinner, made arrangements ("Pay what you like") to park for the night, and ran into the sea.

Beyond the empty restaurants was a ruined boardwalk of bricks steered apart by the moving sand, vegetation leaning away from the wind, and a dance floor under a collapsed pavilion filled to the wall tops with sand, nobody in any direction. At dinner, the teenage son of the landlords lay in a hammock from which he seemed to have never risen, telling us it was open war to the north: his cousins from San Antonio robbed in daylight of everything including the car; a girl kidnapped last week found dead despite the ransom paid; narcos going onto buses and taking migrants for their armies; the dead found month after month in the hundreds; they will shoot you just for fun.

We drank beers as the sun went down, and then the rest of a bottle of Presidente brandy I'd found in the van, and a hundred yards away, the police were driving up and down the surf looking for somebody to rob. Nevertheless, I stood up to walk, panic accumulating in bits: Is this going to be the last stupid thing I do? Am I going to get this kid and myself killed? This wasn't someone in the capital repeating what they'd seen on TV. We were close, hearing secondhand accounts of what lay just up the road. To change plans now would cost hundreds of dollars I didn't have, take us over the Eastern Sierra once more and up, forcing us into the long, toll-roaded center of the country. I sat on the disintegrating wall. Simon joined me. The gray sand extended to a sea that suddenly seemed to be boiling in the dusk, becoming a hell.

I felt as bad, as lost, as I ever have: not only afraid but cursed, entirely at fault, half-certain that a young man I hardly knew would die because of me. How much of this was real danger and how much of it just the warnings we love and conditioned fear? When we got up to walk back, there was not a light on the whole frontage of the town. A truck on the tide line shifted into reverse to follow us. Wild dogs ran at us out of the trees. I dropped into hominid attack stance and growled from deep in my throat, teeth bared in the ancient language all mammals know. We overshot, then found the seafood restaurant again, made brave noises at the owners about the next day, and retired into the van, windows shut against the mosquitoes, each trying for perhaps an hour to sleep.

The alarm we'd set sounded at 5:30 a.m. and was reset in pitch-black for 6:45, ringing again in the theatrical, glittering dawn. Everything restarted simple, no fear, no question of changing plans: A glance at Simon told me he was of the same mind. On the beach, boys played pickup soccer, barefoot at the surf's edge. Far out on the Gulf, the sun slid out of the mile-high fog bank with a crash of brass instruments in the fourth dimension.

I skipped a second swim, showered, and we pulled out. Later that afternoon—after Tampico, I think, the southeasternmost city in Tamaulipas—we sought to explain our sudden, common confidence. Simon, cornered the night before by the same thoughts I was having, had meditated, and then understandably woken up at 2 a.m. to insist we start the engine to run the AC. I'd just drunk myself into a stupor and slept, and my dreams were the kind that move earth: bones broken and reset, the beloved dead talking in their secret tongue, taking me down roads I would not remember in this life. I woke feeling so refreshed, I thought I'd never need sleep again. All I remember of Tampico is getting repeatedly lost crossing through it, and that every cop or soldier at every checkpoint played with the 18-inch rubber crocodile I kept on the dash and did exactly two reps of a bicep curl with the dumbbell that had been loose and rattling the whole ride.

In Ciudad Victoria, we secured a shower, bed, courtyard, pool, and internet inalambrico for $25 each. Now just a hundred miles from Brownsville, the southernmost city in Texas, we got reliable, specific advice from the couple at the desk: Never drive at night. Buy gas, food, and water and use the bathroom in Ciudad Victoria, and don't stop for any reason until crossing the border. It should take four hours. If you see a roadblock manned by anyone except police or military, or anyone wearing improvised masks, go back. Don't pull over for anyone who is not a uniformed police or military officer. If a car tries to run you off the road, fend them off, drive faster—escape, or you will find yourself where there is no help or mercy.

It was a relief to know—and at last believe—just what we were looking at. And yes, we were the first norteamericanos driving through that anyone could recall since forever. I swam in the flowered courtyard until the bats came out and a crowd of children gathered around me in the water, peppering me with questions—and jokes I didn't quite catch—and I made them explode with laughter by mimicking them back, until by the time I went to shower, I had them chanting my name like my private army and agreeing to "like" the bookstore on Facebook.

In the morning, we pulled the van out in front of the cafe next to the hotel for breakfast, and I realized I'd gotten too comfortable and had forgotten to remove the license plates the night before. Two combat helicopters, doors open, guns mounted and aimed out, swept low along the wide street. At a table by the cafe door, two men in their 50s stared with uncomplicated surprise when we came in. The waitress was immediately nervous; the cook slammed the mirrored window to the kitchen shut. I sat with my back to the television, which was talking about the day's murders. I hoped Simon's limited Spanish kept him from hearing, but he could see.

Instantly, the fear was in my stomach again. I am still convinced the people there were not that frightened all the time. They feared what we would bring down, that whoever wanted to kidnap us would kill them, too. After we ordered, it was like an invisible hand turned up the tension in the room: the whut-whut of the choppers from outside, the words from the television—matar, Zetas, ejército. When our food came, I asked for more coffee. I felt if I behaved normally, lifting the cup slowly to my lips, events would proceed only at the speed I let them. "Is this not freaking you out?" Simon whispered fiercely. "These people are terrified."

If I blotted out his fear, mine could not grow. Simon wasn't touching his food. I ate and ate. "You are freaking me out," I snapped. The tortillas were like aluminum, the salsa was acid. I wouldn't meet his eyes.

Simon plunked down a 200-peso note. "Dude, just finish, and let's go." I made a concerted effort to stand slowly and walk to the door. Outside, the Washington plates were broadcasting from both ends of the van. I'd meant to borrow a wrench from the hotel and take them off—my tax sticker was all the legal I'd need until the border. I knelt, thinking I could turn the bolts with a coin. Useless. "Forget it," Simon said. "Everyone is looking at you." This would kill us, my forgetting to borrow a wrench.

We drove. The day wound out through empty fields, the soldiers passing from the other direction in their convoys, lead guns ready to fire, and under duress in the moving vehicle, heeding the advice not to stop for any reason, I attempted to shit into the stone bowl of a large mortar and pestle that was for some reason in the van—but I could not, and so, laughing, we stopped at a convenience store/car wash in the very town of the mass graves, San Fernando, where I gave also the fruit of my bowels to that universal soil. And it was fine.

And when we continued on through that country of red sorghum and wooden farmhouses that looks so much like southern Indiana, my passenger played his amazing compositions on guitar, one after another (his full name is Simon Russell: He will be famous), and I sang him "John Walker's Blues" and "The Old Main Drag" and "Racing in the Street." In Matamoros, things looked ordinary, so I pulled into a supermarket and bought a bottle of Centenario tequila, but looking for the border queue we were stopped by a cop in a hat reading TOURIST GUIDE who threatened us with arrest, and, overwhelmed by instinct and seeing he was unarmed, I jammed the gas and fled.

There is nothing to say about America, for you know it all. I took the other route, the Nuevo Laredo route, coming back: the highway fast and empty, the tolls just $50. I will not take the road along the coast again until the violence has ebbed—as it has in Colombia, and Watts, and other places in this long war—and my adopted country is in a different time. recommended

Grant Cogswell is the proprietor of Under the Volcano Books in Mexico City (www.underthevolcanobooks.com). Stephen Gyllenhaal's movie about Cogswell's 2001 Seattle City Council campaign, Grassroots, opens June 22. Cogswell will read from his book The Dream of the Cold War: Poems 1998–2008 (Publication Studio) at Elliott Bay Book Company on July 2.