Under the blazing sun of the Sonoran Desert, on a weird landscape of rock dusted with ancient cinders and pimpled with blown volcanoes, an unknown party of thirsty travelers paused to bury their dead. On the Camino del Diablo, the Devil’s Highway, death stalks wayfarers at a distance of one small mistake. A broken axle. A snakebite. An ill-timed bout of dysentery. Any delayed arrival at the next far-flung source of water in that unforgiving hell.

The year was 1871. There must have been a survivor, for someone marked the date in the dust with small black lava stones.

In 2008, I came upon those stones untouched where they had been placed nearly 14 decades earlier. Along with renowned photojournalist Anthony Suau, I was on assignment for Time magazine, sent to explore the new border barriers under construction along hundreds of miles of the southern U.S. frontier.

That message from the distant past, untouched, unmoved, unmolested since the days of President Ulysses S. Grant, has come to represent for me the impediments to a well-informed debate over border security. It’s too remote. Most of the U.S.-Mexico border runs through empty, inhospitable terrain. It crosses blank deserts, sawtooth mountains and jagged canyons. In places, it arbitrarily divides ancient tribal homelands and communities of trade of which outsiders know next to nothing.

Only a tiny fraction of Americans have seen these places or know these stories, so the border is a topic ripe for manipulation and demagoguery. The rhetoric at the heart of the government shutdown bears little relationship to the complicated reality. Too harsh for golf or beauty pageants, the border is nothing but ammo for President Trump. As for the lurid writings of Trump’s immigration Svengali, Stephen Miller, they bear no hint of first-hand knowledge. Miller doesn’t seem the type to trek into the spiny glare or climb the reptiled rimrock of the American Southwest. His is the careless certainty of malevolent ignorance.

Trump’s whipped-up rally chant — Build the Wall! Build the Wall! — was pure emotion, untethered to facts. There was never a survey or engineering plan to back it up. No construction firm ever estimated the cost of a “beautiful,” “impenetrable” (Trump’s own adjectives) concrete structure, anchored six feet deep and rising 30 feet skyward over ground accessible only on foot.

One evening, Suau and I helicoptered into the rugged country east of San Diego on patrol with an elite team of Customs and Border Patrol agents. We happened on a small group of border crossers climbing hand over foot up a nearly vertical gully. Taking the group into custody required that the agents descend the same gully, a painstaking and dangerous maneuver that consumed the better part of two hours. There can be no wall-building there.

As soon as Trump blurted his reckless fantasy of a Wall in 2015, I knew that he would wind up parsing and pettifogging in an effort to backtrack. Reality bites, after all. Sure enough, we hear him now explaining that the Wall was never really a wall. It was a barrier. It was steel slats. It was a fence. It was a menu of security measures. And when he said Mexico would pay for it, he meant U.S. taxpayers would pay for it.

Trump’s Wall, in other words, was never more than a provocation, a stink bomb lobbed into the public discourse to rile up his supporters and his critics alike. And everyone complied. What is it about Trump’s crude rhetoric that weaves such a spell? Now Democrats such as House Speaker Nancy Pelosi add to the hyperbole, tossing the word “immorality” around — not to describe the deliberate polarization of the public, which is immoral indeed, but to shut down the entire discussion of an orderly, enforceable border.

Here’s what I learned by going there: The United States had made real, bipartisan progress on border security. The daily “banzai runs” in Yuma, Ariz., that used to send hundreds of young men dashing across the scarcely marked border to overwhelm a few dozen U.S. agents were already a thing of the past. A tall double fence put an end to them. Construction of a dirt service road along hundreds of miles of border allowed frequent patrols that not only reduced crossings, but also saved the lives of migrants who might otherwise get lost in the trackless wilderness.

Today, apprehensions on the border have fallen to levels not seen in almost half a century.

But it’s not a simple problem. As long as per capita income in the United States is many times higher than in countries south of the border, and as long as Americans will pay top dollar for imported narcotics, there will be pressure along the frontier.

Instead of encouraging more cooperation, Trump and his Wall have poisoned the well. And in the desert that passes for our national discourse, a mistake like that can be tragic.

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