While crossing the fence itself isn’t hard, liniment is a sensible item to pack, since illegally immigrating can be hard, dangerous, even deadly work. The problem is evading the U.S. Border Patrol, which maintains a fairly strong presence on the roads within a few dozen miles of the line.

Every 20 minutes or so, a white Chevy Tahoe with the broad green stripe of the U.S. Border Patrol drives past me along the otherwise empty road from Douglas to Naco. (The latter would probably draw more tourists if it had been named Nacho, but its curious moniker supposedly combines the last syllables of ArizoNA and MexiCO.)

The agents briefly eyeball me to see if I’m a smuggler loitering to pick up border-crossers and whisk them away to my safe house. I’m a harmless-looking 6-foot-4-inch white guy driving a tiny Suzuki, however, so I hardly fit their profile.

To avoid being charged with “racial profiling,” airport security personnel notoriously carry out random, arbitrary searches. The Border Patrol, though, doesn’t much pester people who look like me, no doubt much to the relief of the business people south of the border who make their living from U.S. tourists who want to be able to visit Mexico and return home without a hassle.

If you don’t look like you have a legal right to be in the United States, however, the feds are less accommodating. In return for about $1,000, people-traffickers (or “coyotes”) in Mexico promise their customers that their partners in Arizona will pick them up. But the U.S.-side contacts don’t like to venture too far south where the Border Patrol presence is densest. So, the coyotes typically insist that the illegal aliens walk north from the border for one to three nights to arrive at a designated pick-up spot along some lonely road well inside Arizona.

The fairly green plateau southeast of Tucson is not particularly hostile, as deserts go. Indeed, some locals point to the average annual rainfall of 14 inches in Naco, only 1 inch less than in Los Angeles, and dispute whether it’s a desert at all.

On a day when the temperature hits 111 in low-lying Phoenix, Naco, at an elevation of 4,700 feet, is about 18 degrees cooler. In fact, the 15-percent relative humidity and the 20 mph hour wind make for a delightful late spring afternoon.

I feel good, though, only because my rapidly evaporating sweat is cooling me. Here, water — in large quantities — is life.

Empty water jugs litter the scores of trails leading north from the fence. Because water weighs 8 pounds per gallon, illegal aliens crossing in the summer must make life-or-death decisions about how much water to carry. Too little and they die of thirst. Too much and they wear themselves out and could be abandoned by their coyote.

The professional ethics of people smugglers are not much better than those of the region’s numerous drug smugglers. Indeed, many switch back and forth between the two intertwined careers, although, when running drugs, the smugglers work harder to safely deliver their cargo. Coyotes are notorious for abandoning stragglers, or vanishing at the first hint of trouble, leaving their groups to wander in the desert, dying slowly, horribly of thirst.

The following day, four illegal aliens die in the lower, hotter desert to the southwest of Tucson, bringing Arizona’s total for May to 15.

There are other dangers. Some winter crossers froze to death, and others have been hit by lightning. In this lawless atmosphere, bandits prey upon the walkers, and an accidental encounter with heavily armed drug bootleggers could be fatal. The wildlife isn’t friendly either. A local rule at the Turquoise Valley golf course in Naco reads, “A ball lying within a club length of a rattlesnake may be moved two club lengths without penalty.”

“It’s immoral to use death in the desert as a deterrent,” argues the Rev. Robin Hoover, a truck-loving Tucson minister with a cowboy accent and a Ph.D. He heads Humane Borders, a charitable organization that maintains 38 drinking water tanks in the desert to keep illegal aliens from dying.

But there aren’t many other deterrents. When caught, illegal aliens are not penalized. The Border Patrol simply dumps them back across the border to plan their next attempt. If they make it to a big city, they are home free, because the federal government has largely stopped enforcing laws against employing undocumented workers.

Some think this process benefits America. A libertarian activist sent me an e-mail message: “The current system was apparently designed to attract the most motivated, enterprising, brave, and shrewd Mexicans to come live in the United States by erecting theoretical barriers that consist mostly of their willingness to take their lives in their hands to cross the borders and thereafter letting them stay and work.”

Then again, using nothing but death in the desert to deter illegal immigration might mean that, out of 6 billion possible immigrants from the rest of the world, the United States gets those — the most unskilled and the most rash — who think they have nothing to lose.

Paradoxically, the U.S. towns just north of the border are not terribly Mexican. The illegal aliens keep moving to Tucson, Phoenix, and the rest of the United States, where the Department of Homeland Security won’t annoy them.

Californians fleeing the high prices, overwhelmed public schools and monster budget deficit of that immigrant-magnet state are moving to the Arizona border region. Thirty miles northwest of Naco is Sierra Vista, the metropolis of southeastern Arizona. It represents the American Dream, at least as measured in square feet of retail floor space. The main commercial drag already stretches for close to 10 miles.

A young ex-California man with a goatee tells me he is moving his family of six from their beat-up, over-priced rental unit south of San Jose, Calif., to the new home he’d just bought in Sierra Vista. “I got a 2,000-square-foot house on a landscaped half acre for $122,000,” he exults, but then darkens, remembering Californian’s fate. “Don’t tell everybody about this place,” he warns. “You’ll ruin it.”

Less than 16 percent of Sierra Vista’s population is Hispanic, compared to Chicago’s 26 percent. With the U.S. Army’s Fort Huachuca next door, Sierra Vista is 11 percent African-American, compared to 3 percent for Arizona as a whole. As in most military towns, blacks and whites seem to be on a more equal and friendly footing than in many big cities.

Overall, Sierra Vista’s racial situation is more egalitarian than in the bigger urban centers of the Southwest, where a caste system is emerging with the servile jobs filled by Latinos. Although it’s often said that the U.S. economy couldn’t function without illegal immigrants, Sierra Vista is prospering under the umbrella of the Border Patrol. Here “the jobs that Americans citizens just won’t do,” like cleaning motel rooms, are largely done by U.S. citizens. The secret, apparently, is to pay them enough.

The illegal immigrants’ mass trespassing on private property causes problems for the people who work the beautiful but agriculturally marginal land, where each head of cattle requires 40 acres. To stay off the roads where the Chevy Tahoes would find them, the walkers smash through private fences and raid cattle water supplies.

Elgin, Ariz., a dot on the map 25 miles north of the border, is one of the world’s more improbable-looking wine-growing regions. The scenery — blond grasslands rolling off to mountainous horizons — is straight out of a John Wayne movie. The red clay, however, is similar to the famous “terra rossa” soil of Burgundy, so audacious vintners have been growing grapes here for 20 years.

At the end of 2 miles of dirt road stands an imposing Mediterranean-style villa where the assistant manger of the 40-acre vineyard, a college student dressed in skate-punk clothes, enthusiastically pours me samples of the vineyard’s eight varietals. He shows me pictures of the July hailstorm that wiped out what would have been the 2002 vintage. Not long before, a 40,000-acre fire was stopped near the vineyard’s fences.

“Besides battling nature,” he notes, “the other big problem is keeping out the illegal aliens. They come through every night and break the fences. We have dogs, and the illegals are pretty scared of them, but some more came through last night.” The pronghorn antelope can get in through the holes and eat the vines.

Paradoxically, Arizona’s recent inundation of undocumented immigrants is the result of the Border Patrol’s relative successes in California and Texas in the 1990s. The favorite route of illegal immigrants used to be along the cool Pacific Ocean. This turned San Diego’s southern suburbs such as Imperial Beach, where the Border Patrol once caught 2,000 illegal crossers in one 24-hour period, into no man’s lands.

Homeowners repeatedly protested the theft, vandalism, physical danger and psychological violation caused by the masses of desperate men pouring through their backyards every night. So, the government built several big walls along the California-Mexico border.

The bulk of the alien smuggling business then shifted east to the border towns of Arizona, with similar chaos ensuing. Therefore, the government recently erected a corrugated iron wall about 15 feet tall through the heart of Naco and running out into the desert for a mile on each side.

It’s an ugly, rusting hulk, but it’s reasonably effective. “It keeps the immigrants out of back yards and drives them out in the country where you can work them easier,” says a friendly Border Patrol agent sitting in his truck parked under a fabric sunshade. He’s watching to make sure that no one climbs over the Naco wall. (While tall, there’s no razor wire or other deterrents on top of it.)

The officer can’t stand the desert heat because he lives a block from the beach in northern San Diego County. He has been sent from California to help for two weeks, “because they’re really getting hammered out here in Arizona.”

Outside the towns, long lines of sight work to the advantage of the Border Patrol, assuming they can get far enough off the ground to see over the shoulder-high mesquite trees. The Border Patrol’s latest innovation in Arizona is a 20-foot-high extendable “cherry-picker” with a glassed-in observation pod on top. Two of them stand sentinel outside Naco, looking rather like the Martian invaders in H.G. Wells’ “War of the Worlds.”

The guard from the beach hasn’t been to the Mexican side of Naco yet, but then he doesn’t much like Mexican borders towns — “too much drugs and smuggling” — except, he says, for Mexicali, a big, solid city south of Palm Springs, full of factories and colleges.

The whitewashed Mexican side of Naco, with its lavishly wide and empty main boulevard, isn’t full of anything, except for an excellent ice cream shop. Yet, it does have a quiet dignity.

Naco has no shortage of politics, though. In three blocks, I find two statutes to Benito Juarez, who, in the 1860s became Mexico’s first (and last) full-blooded Indian president. Mexico’s largely white elite has been erecting statues of him ever since.

Even more striking is the is election campaigning — posters, storefront party headquarters, and a cruising van with the portrait of the ex-ruling party’s candidate for governor of Sonora expertly painted on the side. All these expensive investments leave me impressed by the Mexicans’ enthusiasm for their democratic freedoms. At least, that is, until I mention it that evening to my wife, who comes from the West Side of Chicago and knows something about machine politics. “Or maybe it just shows how lucrative it is to be an elected official in Mexico,” she observes.

Nogales, the much larger bi-national city an hour due south of Tucson, is divided by an even bigger wall. Mexican nationals are still allowed north in large numbers to shop for necessities in the busy retail stores just north of the border. On the south side of the wall, even a decade after the North American Free Trade Agreement introduced free trade, there’s almost no legitimate retail. There are just gift shops, “pharmacia” selling prescription drugs to tourists without prescriptions, and the bars where generations of University of Arizona college boys have tried to lose their virginity.

Illegal immigration is often talked of as if it’s a vast, unstoppable phenomenon, like global warming, only less under U.S. control. Yet, with more guards, more walls, more electronic motion sensors, more floodlights, more aerial surveillance and, most importantly, more political will, the Border Patrol should be able to succeed at least as well in Arizona as it has in California and Texas.

Presumably, the bulk of illegal intruders would then try to cross in New Mexico. Still, there are only four border states, and New Mexico would thus be the end of the line. So, there don’t seem to be major technical reasons that would prevent illegal immigration from being significantly cut back, if the United States makes the effort.

The ultimate solution to the poverty that drives illegal immigrants northward, however, would appear to lie with the ruling class of Mexico, those sleek gentlemen on the billboards in Naco. The famed Peruvian economic reformer Hernando de Soto told me in 2001, “Basically the whole system … is made for a privileged elite that knows how to navigate within the existing laws, that’s got access to the big-time law firms. But the country isn’t safe for the enterprise of people who have low incomes.”

The Mexican elite could liberate the pent-up productivity of the diligent Mexican worker. Or they could continue to try to use the border as a safety valve to bleed off domestic discontent.