In a remote and rugged expanse of southern Arizona, between the vast stretches of the Sonoran and Chihuahuan deserts, a straight line runs. It cuts through mountaintops, across the foothills and valleys. At one time, the line was conceptual: the border between one country and another, a geopolitical abstraction real mainly to those who ached to cross it and to others who wished to prevent that. Now, in the past few years, much of it has been made physical, filled in across the desert in steel. The documentary short “American Scar,” by the New Yorker filmmaker Daniel Lombroso, explores some of the border wall’s unintended consequences.

In 2016, Donald Trump energized his Presidential campaign with three words: “Build the wall.” On the campaign trail, Trump insisted that Mexico would pay for the project, but once in office he looked to a more likely source of funding, Congress, which for two years declined to offer the money—a battle which eventually sparked the longest government shutdown in U.S. history. Then, in early 2019, the President found a different way: he declared a national emergency at the southern border, a move that allowed him to reallocate funds for the wall’s construction from the Department of Defense. All told, the Trump Administration built more than four hundred and fifty miles of the barrier, about a quarter of the length of the U.S.’s border with Mexico. Construction continued until the moment of Joe Biden’s Inauguration.

Construction projects of this size typically have enormous environmental impacts. But funding the project from the D.O.D.’s budget and classifying it as a matter of national security offered the Trump Administration a way around protections: it made the wall’s construction exempt from the stipulations of the Clean Water Act, the Clean Air Act, the Endangered Species Act, and more than eighty other laws and statutes. “There’s a certain kind of lawlessness that applies to the southern border that does not apply anywhere else,” Stephania Taladrid, a New Yorker writer who’s covered the effects of the border wall, and who reported and produced “American Scar,” told me. “In the aftermath of the 2020 election, and the Inauguration in particular, people were thinking that, with Trump gone, we could afford to just forget about the wall. And, in reality, there were just a series of questions that were left unanswered.” Among them are the impacts on the seventy-plus animal and plant species that the new sections of wall now endanger, including the jaguar, the ocelot, the desert bighorn sheep, and the Mexican gray wolf.

Another is an issue that the project was intended to address: border crossings. Although the wall stops most wildlife migrations, it does not appear to stop people from crossing. Customs and Border Protection maintenance records obtained by the Washington Post show that, from 2019 through 2021, new sections of the border wall—made of steel bollards eighteen to thirty feet high—had been breached nearly thirty-three hundred times, mostly, as the Post reported, with “inexpensive power tools widely available at retail hardware stores.” “The wall has to be understood as a political project,” Lombroso told me. “As a symbol of definitely not anything that’s functional in any way, shape, or form.” In the film, the conservationist Myles Traphagen, who’s been working on the border since the mid-nineties, puts it more bluntly: “Basically, the border wall was the most expensive reëlection campaign prop in history.”

One of the many unanswered questions is what to do with the damage to the land, much of which is in some of the most remote sections of the Sonoran and Chihuahuan deserts, areas that account for a tiny fraction of migrant crossings. The film features striking drone footage from the photographer John Kurc of the tops of mountains being blown off. “You’ve got a four-thousand-foot peak that is a natural barrier,” Kurc says in the film, sitting in one of the blown-out areas. “And now it’s got a hundred-and-fifty-foot to two-hundred-foot canyon carved through it—to put in a thirty-foot fence.” They’re the scars of the film’s title. And, like any scar, “you can lighten it,” Lombroso said, “but you can never really remediate it fully. And that’s what’s gonna happen here.” The wall, at some point, may come down. Its mark will last forever.