Amado Coello is sixty-two year sold, a salt-and-pepper-haired retiree with a gentle, grandfatherly manner that gives him the air of a fairy-tale cobbler. He is in fact a retired paramedic, carrying out volunteer duty at a Mexican Red Cross station set up in a tractor trailer a few miles short of the Arizona border in Mexico.

The makeshift clinic is up a few wooden steps, and it's free. It's open twenty-four hours a day, year round, and attends to a constant river of people who draw up into the tawdry high desert town of Altar on buses in their tens of thousands each month.

The arrivals disgorged onto the sun-baked sidewalk amid a hiss of airbrakes are either prospective migrants seeking to trek across the vast desert to the United States illegally, or they are the failures-those broken by the desert's remorseless wheel and tossed back out by the U.S. Border Patrol.

Sitting at a desk in the cool interior of the truck, Coello is flanked by maps, one showing northwest Mexico in relief, the lay of the land-from the azure waters of the Sea of Cortez to the tall peaks of the Sierra Madre towering a thumb's width above them. The other is a simple outline of Mexico, picking out more than two dozen states in a felt-tipped marker, noting the homes of themigrants who oft en come to the clinic hobbling on crutches after a bruising encounter with the blowtorch wastelands to the north.

"Welcome to the gates of hell. It's the gate to the next dimension." That's Coello, revealing a metaphysical bent as he talks about Altar in Spanish, the deeply expressive language of magical realism. "They don't know what awaits them out there! It could be that it goes well, that they get a good job, or that they stay out there . . . in the desert," he says, warming to his cataclysmic theme. "We get everyone. Entire families, pregnant women in the sixth or eighth month of their term, even older people in their sixties. The first thing we do is we try and convince them not to go, tell them that it is quite risky. We try and find ways to warn them that their families could be left to fend for themselves, but they justify the journey by saying they need an income, that they are going anyway."

The little clinic parked up on the broken asphalt is a triage station for one of the toughest foot journeys on earth. Coello has a small pharmacy with bottles of pills to treat high blood pressure for some of the older people intent on making the walk, together withelectrolyte solutions to help border crossers off set dehydration. Then there are the treatments for those who have been sent back by the Border Patrol with injuries from their trek.

Casting an eye over the tight-stacked shelves, I see wound dressings, anti-inflammatory pills, painkillers, and even eye drops. He has antiparasitic medication for people sick to the stomach after drinking at cattle troughs along the way, and antibiotics to treat cuts ripped by cactus spines and deep sores from rotten blisters.

"The worst are their feet, full of blisters. Their toes are beaten to a pulp with the nails hanging off them. They stumble against rocks in the dark, and that usually hurts the big toe," he says, blithely rattling off a litany of hurts in his lilting, singsong voice.

It is all of more than just academic interest for me. I am in his clinic with a Mexican colleague and friend of mine, Tomás Bravo, for a checkup. We are both reporters: I am part of a team that writes about immigration and the border, and he takes the pictures.

We are planning to follow in the footsteps of countless dirt-poor illegal immigrants from across Mexico and much of Latin America who make this clandestine journey north in search of a better life. It's a trip that I have imagined myself making countless times.

I want not only to see, at first hand, what it's like to break in to the United States, I also want to live that journey as much as I can, as the first part of this wide-ranging look at what smugglers do on the most contentious border on earth, and what the federal police agencies on the other side do to block them. I am doing it this way because I don't think what either does has been adequately reported fi sthand, and certainly it hasn't ever been pulled together in a single book.

Altar struck me as a good place to start. It is a couple of hours' drive short of the Arizona border in Sonora. The sprawl of adobe stores, taco stands, and fl op house hotels lies on illegal immigration's superhighway. It is a kind of desert training post supplying and equipping tens of thousands of border crossers headed northeach year, most with the aid of professional smugglers, in an illicit trade worth billions of dollars annually.

We are joining the band of hundreds of migrants who will be setting out tomorrow to walk the Sonora Desert to the United States. From Altar, we will take a van, or drive if we have to, over the desert to the frontier town of El Sásabe, from there walking forty-five miles up through the empty wilds of the Altar Valley to the hamlet of Three Points, Arizona, where many border crossers are picked up and driven on to Tucson and Phoenix.

It is late July, the most fatal month of the year. It is a time when searing temperatures reach up to 115 degrees Fahrenheit in the shade-only, of course, there is little real shade-and when torrential monsoon cloudbursts fill lonely desert washes with bucking torrents of water in moments. It is Armageddon scribbled across the calendar, the month when two years earlier, the Border Patrol pulled two corpses a day out of the deserts south of Tucson.

I swing my legs up onto the black vinyl gurney for my free checkup. Coello slips on the stethoscope, gazes absently into the middle distance, and listens to my heart. He checks my breathing and then finally wraps an inflatable belt around my arm to take my blood pressure. It is a little bit elevated, 130 over 98, perhaps driven up by my anxiety over the journey that lies ahead, or simply on account of his white coat. Doctors always make me nervous.

Next, Tomás lift s himself onto the gurney. From Mexico City, he is of middling height, with a head of corkscrew curls and a knockout smile, and he somehow quietly glows with well-being. The only concern Coello has is for his slightly accelerated heart rate. He puts it down to the heat, which is in the low hundreds, and cautions Tomás that he needs to start taking frequent sips of water as he is already getting dehydrated. Otherwise he is good to go.

Since Coello likely has more practical experience of what the trail can do to you than most in northern Mexico, I ask him if he has any more advice for us to keep us in one piece on the walk across the rough sun-blasted wilderness that could take us several days-if, that is, we succeed.

He thinks for a moment, then tells us to take several pairs of socks and change them whenever they get damp, as it is the rubbing of sweaty feet on damp socks that accelerates blisters. "The best thing would be to walk in open-toed sandals, but then there are the scorpions and snakes, and then, if you stub your toes . . . ," he says, trailing off , distracted by several new arrivals who have hobbled painfully up the steps into the clinic.

Elmer López is framed by the doorway. He wears a straw hat and a royal blue collared shirt that is encrusted with concentric rings of dried sweat radiating out from his armpits. A peasant farmer from a town on Mexico's border with Guatemala, he is accompanied by his wife and two weary young daughters in matching pink pants that look like pajamas.

The girls flank their mother, their arms draped around her waist, the eldest rubbing a puff y red eye, inflamed by grit from the trail. She is almost asleep on her feet.

Most families hire a guide, or coyote, to lead them over the desert, but the López family was too broke. Instead, the father explains, he led them alone through the desert at night until they were arrested by a Border Patrol agent and sent back over the border after agreeing to voluntary return to Mexico.

He shares some advice with me and Tomás as Coello rinses his daughter's eye and gently applies a white patch with tape, and it's not encouraging. "It's hard to cross right now, more so because of the rains. The washes are deep, and all the bichos are looking for high ground. The snakes will be where you are walking," he warns us. I hadn't figured on that.

Just as Coello is finishing up, another couple of young lads arrive at the clinic, one of them energetically levering himself up the steps on crutches, as if he were giving a particularly athletic performance as Shakespeare's Richard III.

José is a destitute teenage peasant from the southern state of Chiapas who is trying to make his way to a farm job in Florida. He has a large lymph-soaked bandage covering his left knee, which he wants Coello to take a look at. He chats freely as the paramedic unwinds the dressing.

Another self-guided border crosser, José was walking up a desert trail several nights earlier. In the inky darkness, he stepped out over the lip of a deep wash, and tumbled headlong into darkness, in a fall broken by knife-sharp rocks.

As Coello eases off the dressing, I see a deep, sickle-shaped wound carved beneath José's kneecap and reaching around the back of his leg. The sides of the gash are tagged together by a strip of stitches, some of which have tugged free, revealing an angry, suppurating gash.

"It looks bad, but it is healing," he tells me brightly. I look at him, look down at his cut. Trying not to wince, I ask him what his plans are. He shrugs. "I'll probably try again in a few days, once I've rested up."

Speaking of rest reminds me. Tomás and I need a bunk for the night. We say our farewells to Coello and head back out to the street, which by now is as hot as a baker's oven, and see a mirage dancing on the simmering sphalt.

The sign to the Casa de Huéspedes Mar tínez is propped up on a brick in the street. It has a black arrow pointing guests down a dusty back alley from the main strip in Altar to a single-story brick building.

It is a fl op house for illegal immigrants heading up to cross the deserts of the U.S. border, and it is exactly the sort of place we are looking for to bed down for the night. The clerk is sprawled on a couch in a windowless room, watching television. He looks up, somewhat put out by the intrusion, and tells us there are vacancies. It costs three dollars, but a blanket is included in the price, which I would have thought went without saying.

He jabs a hand toward a dark, airless room next door where rows of metal bunk beds stand three tall like storage racks. It gives the place the feel of an office storeroom, or perhaps a jail. I claim the top bunk against the back wall, under a hand-painted image of San Judas Tadeo, the patron saint of lost causes. The figure has a flaming sacred heart in his chest, and his hand is raised in benediction atop a staff. He looks like he is setting out on a trek.

As I stretch out on my back on a thin strip of gray office carpet-the only mattress on offer-I find his prayer is somehow appropriate.

Holy Apostle San Judas, friend and servant of Jesus! The Church honors and invokes you universally as the patron of difficult and desperate cases. Pray for me. I am without help and so very alone. . . . Make use, I implore you, of the special powers to swiftly and visibly help when almost all hope has been lost.

The sun has been beating down all day on the tin-roofed ceiling, backed with black plastic sheeting, about eighteen inches above my nose. I stare up at it, feeling more than a little daunted. The dorm is dispiriting enough. Then there's the journey itself that lies ahead of us.

Before we set off on the trek over the desert, we have to drive for a couple of hours over a potholed road to reach the border line at El Sásabe, passing through an area along the way controlled by well-armed drug trafficking cells and the ruthless human smugglers called coyotes.

The little I know about these thugs makes me nervous. The drug smugglers are loyal to the Sinaloa cartel, and they haul tons of pot each week over the desert back trails to Tucson in specially adapted trucks and SUVs, on horse back, or on foot.

Once over the line, Tomás and I will be in perhaps the only place in he United States where you can still be held up at gunpoint by armed bandits, the so-called bajadores who specialize in stealing drug loads and robbing migrants of their every last peso.

They ambush the groups in the desert, offering them a stark choice: your money or your life. If a group is in a truck the bandits suspect is filled with dope, sometimes the first thing the passengers will know about it is the heavy assault rifle rounds raking up the hood and punching through the windshield.

And then there is the walk itself. It will take us between two mountain ranges that flank the searing Altar Valley, a broad highland plain of prairie grass spotted with cactus and mesquite trees that is baking during the day and extremely cold at night. It is also home to some of the most venomous animals on earth: the rattlesnakes, scorpions, and black widow and brown recluse spiders that can send you to the emergency room with a swift nip or glancing sting. The only thing is, there is no emergency room.

I am, selfishly, very glad that I am not doing this alone. Aside from being a witness to what ever happens out in the desert, Tomás is great company. He also has a straightforward, easygoing manner that is already proving to be a great help on this trip. He is very disarming and friendly, and just hanging out with him is making life a lot easier for me in the grimy bunk house, which is starting to fill up with people.

Our roommates are from a roll call of the poorest states in Mexico, crashing for the night on their way up to the border. Putting down their packs, water jugs, and meager rations of food, they glance up at me with clear suspicion.

I'm above six feet in height, weigh over two hundred pounds, and fill out the top shelf of the bunk. I have fair skin and a shaved head, and totting up the pointers, most people I meet in the borderlands tend to take me for a policeman rather than a reporter. They turn to Tomás for an explanation.

"So what's he doing here?" asks José, a tall youngster from Querétaro.

"We're both reporters. We are doing a story on the journey to the United States."

"Can't you afford to stay in a proper hotel?" he asks, clearly puzzled.

"Yes, but we want to do it like you guys. . . ." Tomás is off, animated, winning everyone over with his charm, easygoing manner, and conversation sprinkled with phrases that mark him out as a paisano, and as a friend. Within a minute or two we are all sitting on the bunk house floor, chatting.

José is a very good-looking kid. Dressed in a black T-shirt and with sharp razor-cut hair, he looks like he could be in a boy band. He is in fact an agricultural worker from central Mexico on his way to Kentucky to muck out horses at a stud farm. He tells me he was working there illegally a few months earlier but came home.

"Why?"

"Por pendejo-because I'm an idiot," he says with a shrug. He got homesick for his wife and young child, and came home to unemployment. Within a few weeks it was time to set off again, rattling north cross Mexico in a bus to once again make the desert hike up through Altar.

Then there is Mario, another farmer with a gentle voice, this time from Oaxaca. He cradles a plump, sleeping baby gently in his arms, and has an awkward, rattled expression. The reason he is out of sorts is that the tiny bundle is the daughter of a woman he met moments earlier in the dorm room, who has now stepped out, leaving him quite literally holding the baby.

A short while later Leticia reappears. She is in her early twenties, earing a white T-shirt, black shorts, and slip-on plastic sandals. Apart from the baby, she appears to have very few possessions. Speaking slowly and with a far-off look in her eye, she tells me that her child is just four months old. The baby's name is Crystal Esmeralda, the only hint of beauty in the guest house, with its stifling dormitory, sweaty blankets, and plastic bucket shower.

The father of her child is somewhere in southern Mexico, and it becomes clear over the next few hours that she has something of a complex life, with a series of entanglements with one or more of the men in our dorm room. Rather than passing through, she has been living in Altar for the past eighteen months. It isn't quite clear when she will be moving on, or how she supports herself.

I stretch out on the meager strip of carpet on my bunk. Exhausted, I pull my shirt up over my head to block out the buzzing strip light on the ceiling, and slip into a deep, dreamless sleep until dawn. It will be a puzzle to me on this trip, but I will have some of the best nights' sleep in years, snatched in a fl op house dorm, then slumped way out in the desert. Tomás is not so lucky.

He is kept up by five boisterous roommates drinking cheap rum and bothering Leticia, who sleeps in a tiny, windowless room behind our bunk. At about 3 a.m., a bare-chested guy in shorts bangs on the door of Leticia's room and barges his way in for sex, but not before turning on a noisy air-conditioning unit to drown out the sound of his activities.

It later occurs to me that Leticia may be a prostitute, a camp follower for this legion of migrants on the march, like the women who gathered up their skirts and followed Napoleon's armies across Europe two centuries earlier, and armies before that, reaching back in an infinite regress.

At first light, Tomás and I gather our few belongings and step out into the street. Only Leticia is awake, and she follows us out to the curb. She has a look of deep sadness on her face that makes me think of Peter Lorre in the film Casablanca, as he promises Rick his "letters of transit."

Have a good trip, and take very good care of yourselves," she says distantly. I don't look back.

An awning stretches over the sidewalk, throwing the row of shops into deep, welcome shadow. We need to get equipped for the trip, and since all the thick-walled adobe stores sell the same things-backpacks, baseball caps, sunglasses, and headscarves-it hardly matters where Tomás and I stop. We dive into the first, blinking in the darkness of the windowless interior. It feels more like a Bedouin tent than a shop. Stacked high on tables and in deep shelves ranged along the walls are black school backpacks priced from five to fifteen dollars, and all the clothes we might need for the trip.

The wares range from cheap hiking boots and knockoff athletic shoes to long-sleeved plaid shirts and heavy denim jeans offering protection against thorns. There are also racks filled with baseball caps and cotton headscarves to keep the sun from burning your skin and sucking the moisture clear out of it until it looks like a wizened old prune.

The proprietor of the store is called Lourdes. She sits in a plastic patio chair in the dark interior of the shop, which somehow has the feel of a traveling bazaar that could be packed up and sent on across the wastes on camelback.

Far from simply being a cut-price outfitter for migrants, this souk sells items that are also a rich repository of folklore, offering a dazzling array of consolations for the journey.

Lourdes, like all the other store owners, sells a selection of caps and headscarves decorated with images of the Virgin of Guadalupe, Mexico's most revered icon, depicted in a shawl fringed with rays of light, and with an adoring Juan Diego kneeling at her feet, interestingly, in a desert dotted with nopales.

San Judas also features prominently, offering forlorn hope to the dispossessed. One headscarf, though, is eye-catchingly different, capturing the hopes and dreams of material betterment that are implicit in the journey that hundreds of thousands of illegal immigrants make each year. The cotton rectangle is printed with a flurry of twenty-, fifty-, and hundred-dollar bills, set against a backdrop of green. Migrants who buy it are literally wearing the American Dream on their heads as they set out for the north. I finger its meager selvedge, lost for a moment in that enticing reverie of riches. I slip it over my head and anchor it in place with a cap. I decide to buy them.

In a bewildering irony of globalization, I notice that the scarf is made in China and the cap in Vietnam. I find the thought of factories in the Far East running off caps and scarves for a target market of penniless migrants from Mexico mind-boggling. First, how did they ever find out about their journey? Then, how do they turn a buck out of pitching to the borderline destitute?

Other popular items on sale are soccer shirts for teams in Mexico's Primera Division league. Lourdes has the blue and white stripe of Cruz Azul, a team from southwest Mexico City, and the red and white colors of Las Chivas from Guadalajara, famed as the one club in Mexican soccer that has only ever signed Mexican-born players.

"We sell a lot of them," Lourdes says as I hold one of the shirts in my hands. "They like to wear their colors. Their teams carry their hopes and their dreams."

Seeing the shirts reminds me uncomfortably of the story of a condemned man on death row in the Jim Crow South de cades ago that had touched civil rights leader Martin Luther King, Jr. In some macabre twist, the prison authorities had decided to place a microphone in the gas chamber just before the man's execution, to capture his last words. As the pellet dropped to release lethal cyanide fumes, he was overheard making a desperate appeal to then world heavyweight champion Joe Louis. He expired whispering, "Save me, Joe Louis! Save me!"

Could it be, I wonder, that soccer-mad Mexican migrants in extremis in the desert call out through cracked lips to top goal scorers like the Chivas' Salvador Reyes for salvation? It's a strange and disquieting thought.

It's time to pay up and get our provisions. Earlier, I had picked up a guide at the Catholic church refuge, which contains a helpful shopping list. It advises migrants to stock up on canned food, candy, peanut butter, chocolate, and suero (electrolytic rehydration powders), and of course water. If the water runs out, the guide advises migrants to suck a pebble as they walk, to stop their mouths from drying out-an old Native American trick.

We head along the broken sidewalk to Pesqueira Hermanos, the largest supermarket in Altar, to fill our rucksacks with food and fluids for our trip. It's strange. As we head into the store with our church shopping list, there is something different, out of place. Then I realize what it is.

I lived in northern Mexico for a couple of years. In most supermarkets you tend to see middle-class house wives haciendo super, as the weekly shopping is known, often dressed and made up to equal the glamorous presenters on Televisa. Here, though, the aisles are packed with tight knots of men pushing carts conspiratorially, locked in animated discussion about the items they need for the grueling journey ahead. We follow them around with our shopping list, starting off with water.

You see the gallon water jugs strewn across the deserts in southern Arizona, an unwelcome addition to the landscape, by now as commonplace as the saguaros themselves. Here they are, stockpiled in huge quantities in the far corner beyond the produce department in a massive display.

The opaque plastic containers rest on pallets stacked ten tall against the wall. I see that border folklore is also to the fore here. The local brand, Agua Purifi cada Santo Niño de Atocha, is pure marketing genius, specially targeting superstitious migrants. The brand is named after the holy child who appeared to a group of miners trapped by a cave-in at a deep mine in the desperately poor central state of Zacatecas. In answer to their prayers, the tiny figure led them through the mazelike underground galleries to safety.

Perhaps not coincidentally, Zacatecas is one of the states with the highest rate of emigration to the United States. What better figure to accompany Zacatecans on a walk through the hazardous desert labyrinth, then, than the image of their very own holy child? Slapping the figure on a bottle is inspired.

Another brand of water that one Arizona rancher told me he had come across comes in a gallon jug stamped with a picture of Baboquivari Peak, a sugarloaf-shaped dome sacred to the Tohono O'odham tribe that towers over the route north through the Altar Valley.

For those making the trek on foot, the jug in their hand serves as a basic map, accompanied by text advising migrants to keep the peak on their left-hand side during their three- to six-day walk up through the valley to Three Points and other load-out points on Highway 86 as it sweeps in across the desert toward Tucson.

I look around for the brand in the store, but can't see it. I figure that perhaps it's like a Coke and Pepsi thing. In Altar you either stock Santo Niño or Baboquivari water or lose your refrigerator. We load six gallons into the shopping cart and trundle on down the aisles. We figure it may be just enough fluid if we walk in the cool of the night and sleep during the day.

Tomás and I agree on a dozen cans of tuna fish and four large cans of refried beans. We also load up on a packet of fl our tortillas, broad discs bound with suet, which we agree will make good fat burritos out on the trail. Chocolate, except in fiddling packets of cookies, is nowhere to be found, so we settle on a cone of piloncillo-raw cane sugar.

It has the rough texture of a cattle salt lick, and we figure it will be good for a no-frills energy burst should we need it out on the trail. Now all we need is garlic. It's an odd one, but it comes on doctor's order: Coello himself told us to buy it.

The stinking rose is high on every migrant's shopping list, as it is held to be an effective repellent for the night-walkers: the poisonous spiders, scorpions, and reptiles that hunt out on the trails the migrants walk over. Groups of migrants are in particular danger of treading on them or even sitting down on them, as they travel at night without a flashlight so as not to draw unwelcome attention to themselves from border police.

The technique, according to Coello, is to slice a fat, fresh clove in two and rub your feet, socks, shoes, and pants with the gleaming juice. When this is done thoroughly with a fistful of cloves, the clothes are said to be pungent for life, although whether this is effective at warding off predators is difficult to either prove or disprove.

Garlic does, however, have one proven property that could provide an unsought benefit to migrants: It is a natural and effective antibiotic. The presence of the microbe-fighting juices may well help migrants who continue to walk on, day after day, with ripped blisters steeped in increasingly bacteria-rich socks. We toss four or five heads of garlic into the cart as it can't hurt. Next stop, the pharmacy.

The Border Patrol say that walking in temperatures above one hundred degrees, you can lose up to a gallon of water an hour. The life-giving moisture evaporates through the pores, leaving vital salts encrusted on clothing in stale rings like those on López's cotton shirt. The suero on sale includes a balance of all the essential metabolites, combined in a strict ratio with sugars to aid their speedy uptake by the body.

The supermarket pharmacist is dressed in a white lab coat, and stands before neat, well-stocked shelves eyeing me somewhat impatiently. She holds up two kinds of suero to a circular hole cut in a glass window that seems to seal off the unwashed shoppers from her sterile domain. The choice is plain or lemon flavor. The lemon costs three times as much, but somehow it looks more refreshing, so we buy several boxes of sachets to add to the distinctly holy-looking water.

I also wonder about pep pills for the journey, and I ask her straight out about the best of them: ephedra. The compound was sold over the counter stateside as a weight- loss product and energy booster for years, and it is rich in ephedrine and pseudoephedrine, the principal ingredients of methamphetamine that fire up the metabolism like a blazing gas poker stuffed into a reluctant coal fire.

Aside from its use as a slimming aid, it has been used for its supposedly performance-enhancing effects by troops on exhausting military exercises and by athletes in training. Border Patrol agents that I have spoken to say that it is also sometimes fed to migrants by coyotes seeking to get groups of people to cross open ground faster.

Ephedra, though, was banned for a reason. The preparation has a range of dangerous side effects, including heart attacks, strokes, and overheating, and has been implicated in the deaths of soldiers and athletes including Orioles pitcher Steve Bechler, who died during spring training in 2003 after taking the drug.

The pharmacist looks at me blankly. I dictate the letters E-P-H-E-DR-A for her to note down. She looks the name up in a guide, but finds she doesn't have it. What she does have is a codeine pill, laced with caffeine, which she says will also do the trick. I can't make up my mind about it. I don't like popping pills unless I really have to, and decide to pass.

It's time to get a little last-minute professional advice before we hit the border.

Tomás and I head out to the square and loiter in the shade of some eucalyptus trees on the corner opposite the Banorte office. It's a spot where Altar's coyotes congregate, doing business beside a line of white Ford minivans that run migrants up to the border line.

You have to be careful talking to smugglers, as our TV cameraman Manuel Carrillo found out last time he was in the town. Then, as he was standing in the plaza filming, a man on a bicycle rolled up to him, flashed a long, sharp knife, and warned him and the reporter he was with to skip town.

We are rather furtively on the lookout for Carlos, a smuggler with whom Tomás, ever friendly and disarming, was talking the day before. We catch sight of him leaning heavily on a pay phone, barking into the receiver. Muscular and short, he wears a pair of reflective sunglasses. He has close-cropped hair and rolls of skin that gather up on his neck like the thick roiling furrows on a shar-pei pup. He is dressed in a pressed white T-shirt, notable for having been ironed, and some khaki shorts and smart sneakers. It is a purposeful, distinctively cared-for look that makes him stand out amid the crowd of broke and shabbily dressed migrants. To me, he looks like a well-turned-out fighting dog.

Originally from Guatemala, he has been running migrants over the border from Altar to Phoenix for the past five years. Tomás greets him with a smile and handshake, and explains that we are going to cross the border that day. Would he, perhaps, have a little breakfast with us? He nods.

Strolling along the main strip, Carlos eyes the stream of well-equipped buses from the south unloading their cargo of farmers and the urban poor from across Mexico, heading on up to the United States for work. He looks at them, looks at me, then whips out his wallet and opens it to fl ash a thick wad of banknotes. "They think they have to cross to the other side to make money, but they don't. There's plenty to be made here in Altar if you know what you're doing," he brags.

It was no coincidence that we found Carlos using one of several Telmex phone cards to work the shiny bank of telephones in the street. He has one family in Guatemala and also a wife with children in Maryland he hasn't seen in three years. Aside from keeping in touch with them, his chosen profession is one that requires a large network of coworkers carrying out a variety of tasks that require close coordination on both sides of the border.

There are the ganchos, or "hooks" in English, who recruit the migrants in their home owns across Mexico and beyond, some working right down in the highland cities of Central America. Then there are the coyotes proper, the guides who lead them over the desert, usually on foot, although occasionally in trucks or even bicycles.

Then there are the short-haul drivers who spirit them on from desert load-outs to Tucson, or more commonly Phoenix, where they are held prisoner in drop houses until their fees are paid by their sponsors, usually anxious relatives already living in the shadows stateside.

In a conversation with Tomás a day earlier, Carlos explained that he operates a two-tier charging system. For somewhere around $1,200 a head, a guide will walk migrants over the desert as part of a group, in a trek taking several days, before handing them off to drivers taking them on up to Phoenix.

If they are prepared to pony up a few hundred dollars more, there is an express trip by truck that will take just a few hours. As we plan to go it alone-an increasingly long shot in a time of ramped-up border security-Carlos volunteered to show us the best places to cross, and, naturally, those to avoid.

The taco stall is open to the street. The lemon yellow walls of its sunlit interior are decorated with a picture of Jesús Malverde, the drug traffickers' saint, and a poster of Valentín Elizalde, the Stetson-wearing balladeer of the powerful Sinaloa cartel who was gunned down a few months earlier after recklessly playing a concert in rival Gulf cartel territory south of Texas.

The display is a subtle message that the owner of the stall is open to the boys from Culiacán, the violent capital of Sinaloa state, who have moved into Sonora and secured local trafficking routes at gunpoint for drug lord Joaquín "El Chapo" Guzmán, Mexico's most-wanted man.

Carlos hasn't removed his sunglasses. He reaches across the fl oral tablecloth for my notebook and pencil. Hunched over, he sketches out a map with an almost childlike concentration. It shows the road we will need to take to El Sásabe in meticulous detail, and marks out key trafficking back roads branching out like the limbs of a saguaro as they lead up to the international line.

On the far side of a penciled fence marking the international border, he blocks out the serried peaks of the Baboquivari and San Luis mountains that stand over either side of the Altar Valley like a fistful of smashed knuckles.

"If you cross through here, you are entering the lion's mouth," he says, tapping the pencil sententiously over the tiny border town. "There's a lot of migra, and nobody crosses through there anymore. They are there day and night with motorbikes, quad bikes, and in cars tracking you, and they also have a helicopter and dogs."

Three greasy meat tacos cool in front of him on the oilcloth as he sketches trails out to the west through the vast, empty deserts of the Tohono O'odham nation, west of the sugarloaf dome of Baboquivari Peak, and east toward Green Valley and the border city of Nogales. He suggests we take either one of them to avoid the ramped-up vigilance.

"They have left a little space on either side, and that's where people get through." Carlos's advice to us is to hug the mountains flanking the valley, where access trails for the Border Patrol are further from the main highways, and more difficult to watch and to track.

He warns us that it could likely take up to six days to cross up to Highway 86, the main corridor taking migrants out of the desert and into Tucson. It will be tough, he says, but we just have to be determined like the highly motivated migrants who get through.

"They succeed because they have the same dream you have," he says, revving us up like an L.A. life coach. "The american Dream."

Excerpted from Midnight on the Line by Tim Gaynor

Copyright © 2009 by Tim Gaynor

Published in March 2009 by St. Martin's Press

All rights reserved. This work is protected under copyright laws and reproduction is strictly prohibited. Permission to reproduce the material in any manner or medium must be secured from the Publisher.

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Excerpted from Midnight on the Line by Gaynor, Tim Copyright © 2009 by Gaynor, Tim. Excerpted by permission.
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