More than a year after the former President left office, Republican governors, federal regulations, and inaction in Congress are allowing construction to continue.

Myles Traphagen kept his eye on the horizon as he maneuvered his pickup truck down a treacherous sand road in Cabeza Prieta, Arizona’s largest wilderness area. Bordered by Organ Pipe Cactus National Monument to the east, Cabeza Prieta sits on the state’s southwestern edge. The preserve, which was founded in 1939, is known for its beauty and its desert wildlife, which includes Western diamondback rattlesnakes, Sonoran pronghorn, and lesser long-nosed bats. It is, according to the National Park Service, the “loneliest international boundary on the continent.” Looming mountains, some made of lava, others of granite, cleave the rugged land. They give Cabeza Prieta its name—Spanish for “dark heads.”

Halfway down a road leading to the border with Mexico, Traphagen stopped his truck. A burly man of fifty-four, with thick brown hair and a scruffy beard, he raised a pair of binoculars to his eyes. “I think that’s it,” he said. Traphagen was pointing to a winding dark line that, from a distance, looked like a stain on the earth: the border wall. “It’s like you come down here to see it and then you don’t want to see it,” he added. A biologist by training, Traphagen has spent the past four years mapping the four hundred and fifty-eight miles where the Trump Administration erected a wall from Texas to California—a barrier that he warns is having a disastrous impact on the environment. “Animals have been migrating through this route for tens of thousands of years,” he said. “If we cut off this population, we’re essentially altering the evolutionary history of North America.”

Driving behind Traphagen, in a gray S.U.V., was John Kurc, a photographer in his sixties who once travelled with rock stars. Kurc, who wears his hair in a low bun, spends his days tracking the wall’s environmental damage, from waterway pollution to disruptions of migration patterns. “I can see it snaking over the mountains off to the west,” he told Traphagen, via a handheld radio. The two men drove through an expanse of desert dotted with ocotillos and towering saguaro cacti. The Tinajas Altas, one of the area’s granite mountain ranges, appeared in the distance, dwarfing a thirty-foot-tall stretch of barrier that bisected the ridge. “Like we needed to have a wall when there’s already the best natural wall you could ever have,” Traphagen said.

Unlike in Texas, where the vast majority of properties bordering Mexico are privately owned, almost all border areas in Arizona belong to the federal government. This is where the Trump Administration, likely to avoid protracted court battles, focussed its wall construction. During Trump’s four years in office, half of the wall building took place in Arizona, and his Administration completed all but eighteen miles of what it planned in the state. Since most crossings take place in Texas, the wall in Arizona, Traphagen contends, is doing more damage to the environment than to smuggling networks. All told, in the name of building the border wall, the Trump Administration waived more than fifty environmental laws and regulations. “It’s every major environmental act that’s ever been passed,” Traphagen said.

On the day Joe Biden took office, he revoked the emergency declaration that Trump used to justify barrier construction, following through on a campaign promise not to build “another foot” of wall. But, more than a year later, construction continues. Republican governors are in the process of building new sections of barriers in their states with hundreds of millions of dollars in government and private funding. Federal regulations have delayed attempts by the Biden Administration to cancel numerous wall-construction contracts issued by Trump in his final weeks in office. And liberal Democrats, environmentalists, and landowners near the border say that the Biden Administration is not moving aggressively enough to reverse the damage caused by the wall. “They are riding the fence on this,” Traphagen said.

In Congress, divisions among Democrats have slowed Biden’s efforts to permanently end his predecessor’s project. After taking office, Biden tried to reallocate several billion dollars in funds that Congress had appropriated during the Trump-era to build additional wall. By law, the President is required to spend that money on a “barrier system” at the border, and Congress has not rescinded or repurposed the money. As a result, Customs and Border Protection is taking steps toward the construction of eighty-six miles of wall in the Rio Grande Valley using funds appropriated under Trump. Environmentalists in Texas have said that they hope Democrats in Congress will repurpose the money before the new wall is actually built. But a former senior White House official predicted that conservative Democrats in the Senate would likely oppose such a move. “You have enough moderates who are going to argue, ‘We need some border barrier,’ ” the official said. “An idea of something being better than nothing.”

The Biden Administration also decided to minimize the hazard caused by unfinished construction by filling gaps in the wall left by Trump in Arizona, Texas, and California. The former official said, “It ended up being a legal conclusion that some of the construction was going to have to be finished, or else it would create a legal risk.” The former official regretted that the Administration hasn’t appointed a political liaison to oversee initiatives related to the wall—an oversight that left many border residents unclear about the White House’s intentions. “There was a question about who owned it. That was a problem across immigration issues,” the official said. “And it speaks to a lack of political awareness about the border region. It’s a lack of political respect for border communities.”

Asked for comment, a White House official said, “On his first day in office, President Biden paused construction of a wall along the Southern border, and every day since we have been working to clean up the mess the prior Administration left behind, including by returning, where possible, the land it seized, returning the money it took from our military, and working closely with border communities, stakeholders, and Tribal communities to address urgent life, safety, and environmental issues.”

Republicans, meanwhile, are extending Trump’s barrier. Last summer, the governor of Texas, Greg Abbott, who is running for reëlection this November, said that he would use state and private funding to resume border-wall construction. The Texas governor has obtained seventeen hundred unused wall panels from a federal agency that distributes surplus material. Following Trump’s playbook, he has declared a state of disaster on the border, and reallocated state funds for barrier construction which the legislature had originally designated for other uses. So far, Abbott has secured more than a billion dollars in state funds and fifty-four million dollars in private donations.

In Arizona, Governor Doug Ducey and state legislators hope to use somewhere between fifty and seven hundred million dollars of public funds for additional barrier construction there. Across the Southwest, Republican officials continue to see the potency of immigration as a campaign issue. “Fear,” Kurc said, “is very profitable in the United States.”

Kurc’s first visit to the area, in 2019, had little to do with the wall: he was there to photograph the Rolling Stones. Curious to see for himself the “invasion” that Trump kept talking about, he visited the border town of Douglas, Arizona. “I took a dirt road and drove right up to the wall,” he recalled. “There was no Border Patrol, no Mexican Army, no drug smugglers, no migrants coming over. I started videotaping, and I was, like, ‘Look, this is not what we’re being told.’ ” Kurc, who has adult children and was newly single, returned to his home, in Charleston, South Carolina, put a mattress in the trunk of his car, and drove back to the border with two cameras and no return date in mind. “I was so intrigued by the non-invasion that I came back the next month,” he said.

Soon afterward, Kurc and Traphagen met for the first time, at Guadalupe Canyon, some four hundred miles east of Cabeza Prieta. Traphagen had been working along the border for decades. A California native, he started his conservation career in southeastern Arizona, in the nineteen-nineties. He met his wife, Martha Gomez Sapiens, an ecologist, there, and the two had a son. When Trump’s border-wall construction reached Arizona, Traphagen began advising a coalition of local ranchers and scientists about its impact. Around that time, Kurc was in Guadalupe Canyon taking pictures of the landscape with a drone, when he heard an explosion. For the next several days, he watched workers and engineers drill holes in the rock, place explosives there, and set off three or four blasts a day.

On a visit to the canyon, Kurc recalled what the area looked like during that time. Hundreds of R.V.s. filled the site. Using backhoes and bulldozers, workers carved out roads leading to multiple wall-construction sites. “This was like a huge city,” he said. The new barrier blocked large portions of a critical habitat for various species in the southern Peloncillo Mountains—the only link between the Rockies and the Sierra Madre Occidental.

An estimated three hundred and fifty miles of barriers were completed in the final year of the Administration. Multimillion-dollar contracts were awarded up until the last days of Trump’s term. Many observers believed that Trump was trying to make it difficult for his successor to unravel his project. The new President would face hundreds of millions of dollars in payouts to contractors. “This was a mad rush,” Kurc recalled, referring to the pace of construction under Trump. “There were even crews working at night.” While Biden was being inaugurated, Kurc observed the last dynamite blast on the border.

Landowners, tribes, and environmentalists impacted by the construction argue that the Biden Administration’s response has not been forceful enough. Many among them would like to see entire sections of wall torn down, but the Administration has so far ruled out that idea. Others, like Traphagen, have asked that at least some gaps be left in place so that large animals can roam their natural habitat freely. Currently, only cottontail rabbits can make it through the barrier’s four-inch-wide bollards.

For years, Traphagen, using trail cameras, had captured images of javelinas, bobcats, mountain lions, Coues white-tailed deer, and Sonoran mule deer traversing the border. Since the construction of the wall, he’s lucky if he spots a skunk. “The southeastern corner of the state is where the jaguar and the black bear share the same trails,” Traphagen said. Scores of streams were also dammed, irreplaceable fossil groundwater was depleted, and the removal of vegetation created a risk of erosion. During last year’s rainy season, flash floods ripped several of the wall’s floodgates off their hinges near the San Bernardino National Wildlife Refuge. “It’ll choke off streams, watercourses, and springs,” Traphagen said, of the construction debris. “And the effects are going to be felt on both sides of the border.”

In the Mexican city of Agua Prieta, which sits across the border from Douglas, environmentalists told me that rivers that flowed south from Arizona into Mexico had been contaminated by rust from Trump’s wall. José Manuel Pérez Cantú, the conservation director of Cuenca los Ojos, a binational group that oversees dozens of miles of protected lands, said that three of Cuenca’s properties had been walled off by Trump’s barrier, including one across the border from Guadalupe Canyon. A rangy fifty-five-year-old, Pérez wore a creaseless white shirt with Wranglers and a straw sombrero. “We haven’t learned to read nature,” he said. “It’s been yelling at us for years.”

When we visited the San Bernardino River, which flows south from Arizona through one of Cuenca’s properties, the water had an orange tinge, and native fish were nowhere to be seen. During the rainy season, Pérez said, floodgates and sections of wall have been toppled by surging waters. Using Kurc’s footage, Pérez had brought a complaint to Mexican authorities, but officials told him that there was nothing to be done. The damage, they insisted, was only on the American side.

As a protective barrier, the wall had proved ineffective, Pérez said. U.S. Border Patrol agents have already recorded thousands of breaches by smugglers, who use basic hardware like grinders and acetylene torches. Crossings through Cuenca’s properties, Pérez added, have only increased. Roads created by wall contractors on the U.S. side now serve as routes for human and drug smugglers. “Whereas we previously saw one group a month,” Pérez said, “we now see people crossing every day through the roads carved by the workers.”

What is now referred to as el muro, the wall, was once known in the borderlands as la malla—the mesh—the scholar Norma Iglesias-Prieto wrote in a collection of essays. In 1849, in the aftermath of the Mexican-American War, the two countries placed hundreds of markers, including obelisks of stone and marble, along the newly negotiated border. Nearly two centuries later, barbed-wire fences and walls, some of which were built with steel helicopter landing pads from the Vietnam War, have dwarfed the nineteenth-century markers.

For Reynaldo Anzaldua, a seventy-seven-year-old who lives in the Rio Grande Valley, that history is deeply personal. More than two hundred years ago, Anzaldua’s ancestors settled on the Texas side of the river, on a Spanish land grant of more than half a million acres. Anzaldua estimates that they came to own about a third of the Valley’s land. In the following century, thousands of acres were lost to taxes and land grabs. Along with other local residents, Anzaldua saw the border become a militarized zone. He also witnessed his family’s land be confiscated; by his count, they have lost about two hundred acres in recent decades, primarily to U.S. federal and state land seizures. “Our parents, grandparents, and great-grandparents—we’ve all had to fight the same battle,” he said.

One morning, Anzaldua picked up his cousin Jose Alfredo Cavazos from his home. The two men, both retired, spend hours on the dock of their property in Mission, Texas, which stretches for more than a mile along the Rio Grande. On their way to the river, they recounted the U.S. government’s efforts to seize their land dating back to the George W. Bush Administration, which passed a law in 2005 that allowed the Department of Homeland Security to waive dozens of laws to expedite construction. They got a brief reprieve under Barack Obama, who erected more than a hundred miles of fencing, but nowhere near their land.

After Trump took office, Anzaldua received a letter from U.S. Customs and Border Protection that read, “We hope that you and other landowners in the Rio Grande Valley will assist us in our strategic efforts to secure the Nation’s borders.” Hundreds of Texas families who owned property along the Rio Grande received the same notice. After the family refused to allow any workers to enter, they had to fight the Administration in court. Eventually, the Administration filed a lawsuit to seize part of the property under eminent domain.

At the same time, Steve Bannon, Trump’s former White House strategist, and three of his associates launched a multimillion-dollar campaign to build a private border wall on a neighboring property. Bannon, who was later accused of defrauding donors but was pardoned by Trump, constructed less than five miles of wall. Anzaldua could see the construction, shoddily done, from his dock. “It’s foolish,” he said. “The river will end up washing it away.”

Last April, a federal judge ruled that the government could seize a portion of the family’s land through eminent domain. But the Biden Administration decided that their properties were no longer needed by the federal government—a reversal that has benefited forty families to date. The announcement brought temporary comfort to the Cavazoses. But many families in the Valley fear Governor Abbott’s construction plans. Shortly after Biden took office, Abbott sent a letter to the President demanding that the federal government return to Texans any land “not used for building a border wall.” The former senior White House official expressed dismay about the continued violation of private property rights. “So many of our democratic values go out the window at the border,” the official said. “But even libertarian and conservative values go out the window, too.”

Some forty miles to the west, I met Nayra Alvarez, a teacher in her fifties who lives in the community of La Rosita. Together with her father and her grandfather, Alvarez owns about eight acres along the Rio Grande. In 2018, the Trump Administration tried to condemn and seize their land, but the family spent years in court battling the government. At one point, surveyors told Alvarez and her neighbors that, if they didn’t take the hundred dollars the government was offering in exchange for permission to enter and study the property, it would inevitably seize the land, anyway. She believes that the Administration targeted her county because it is one of the poorest in the state. “I think that when they picked Starr County to start building the wall, that informed it,” Alvarez said. “They didn’t realize there were a lot of educated people, and that they were willing to fight.”

In September, a federal judge dismissed the former Administration’s attempt to seize her property, but Alvarez doesn’t trust the Biden Administration, either. Recently, contractors began building a thirteen-mile concrete barrier topped with guard rails that the new Administration calls a levee. Alvarez, along with other local residents and conservationists, sees it as a ruse by Biden to keep the wall in place. “You can’t plan for tomorrow, because you don’t know what is going to happen,” Alvarez said. “It’s a waiting game.”

Forty miles to the northwest, business owners and construction workers in the ranching county of Zapata, Texas, told me that they welcomed renewed wall construction by Biden or Abbott. A construction manager, who asked not to be named, said that people in Zapata, a border community of more than five thousand, need the high-paying jobs that the construction creates. In 2019, the company that the manager worked for was awarded a six-hundred-million-dollar contract to build forty-two miles of barrier in the county. “That just doesn’t happen here,” he said. “It was an opportunity to make history.”

The wall’s construction proceeded far more slowly than expected. By the time Trump left office, “we got under two miles done,” the manager said. When Biden halted wall construction, workers blamed him for eliminating jobs. “They stopped us too soon,” the manager said.

At a taqueria along U.S. Highway 83, I met two of the workers the man had hired: a father and son who also lamented the end of construction. The father, fifty-nine years old, said that he was originally from Tamaulipas, Mexico, and had migrated north with his parents as a child. His son, who had just graduated from high school, wore braces, a silver cross pendant, and a pair of Oakleys on top of a cap. The minimum wage in the area, they explained, was a little more than seven dollars an hour; wall contractors paid more than twenty. “We were thrilled,” the father recalled. When his children were young, he had worked in the pipeline industry, in various roles. The work kept him away from his family for a week or more. When he was building the wall, he could return to his family every night, for the first time in years.

The father and son acknowledged that the wall was poorly managed by construction companies, at least one of which donated to Trump’s campaign. “They didn’t have the slightest clue,” the father said. He didn’t understand how the Biden Administration could simply rescind the contracts, when pretty much all the material was already on-site. “If they want to tear it down, have them call me,” he said.

Last winter, the father and son went back to working on the wall. Abbott had awarded a hundred-and-sixty-million-dollar contract to build eight miles of his wall. The father felt lucky, he said, and hoped to work on it for at least a year. He remembered Abbott visiting the construction site twice. “He signed some papers and left with a smile,” the father said. Last week, after the workers had completed only a mile-and-a-half-long stretch of Abbott’s wall, state officials announced that work on that part of the barrier was nearly finished.

The father, who is now unemployed, said that he had found dignity in the work—not in the project itself but in the life style that came with the pay. He relished seeing his wife, children, and grandchild each night. But there was something about the job that troubled him. This year, several migrants have fallen while trying to climb the wall, and lost their lives. In April, sheriff’s deputies near Douglas, Arizona, found a thirty-two-year-old woman from Sinaloa, Mexico, hanging upside down from the barrier. After apparently climbing up the barrier with a ladder, her foot and leg became ensnared in a gap between the steel bollards, leaving her “trapped upside down for a significant amount of time.” A local coroner said she died of traumatic asphyxia, a medical condition in which excessive blood accumulation in the head and neck causes a person to choke to death.

The father said that from a distance, while building the wall, he could see the town in Mexico where he was born. He still has relatives there. “On the other side of the river is Tamaulipas,” he said. “I often think to myself, Look what you’re doing to your own people.”