As the president fights to build a wall between the United States and Mexico, correspondent Azam Ahmed and photographer Meridith Kohut drove the approximately 1,900-mile border and sent dispatches from crossings along the way.

In Tijuana, the border is a stage for political theater. The show’s producer? President Trump.

A tourist takes a photograph through the border wall at the beach in Tijuana.

Meridith Kohut traveled back to Venezuela, where she is based, to cover recent events. Adriana Zehbrauskas stepped in to photograph the final leg of the journey.

TIJUANA, Mexico — A busy Friday at the Tijuana crossing between the United States and Mexico: Some 90,000 people stream across the lofted footbridge, a mix of tourists, shoppers, workers and students moving in a symbiotic rhythm.

They spend, work and study on both sides of the border, with this back-and-forth flow happening in the face of arguably the most fortified part of the wall that sits between the United States and Mexico along the nearly 2,000-mile border.

Reinforced walls have been a relatively recent addition to the local landscape. From the crossing between San Ysidro in San Diego and El Chaparral in Tijuana, one can see earlier, less foreboding iterations of the wall, like the one signed into law by President Bill Clinton in 1993.

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In the years since, the wall has been added to, adjusted and amplified — a living testament of sorts to the enduring and often political nature of wall-building along the border.

On the immigration issue, Tijuana has long been a hot spot of political and media attention, a sort of stand-in for the border writ large, however mistaken the idea.

And it was no different on a recent visit.

Two sisters in the house they share with their family in Tijuana, just a few feet from the border wall. The family has been living there for 25 years yet has never been to the United States.

Thanks to the arrival in the city of thousands of migrants, traveling in caravans for safe passage from Central America, and because of the hectoring focus of President Trump, Tijuana has attracted the bulk of attention.

It has become the flash point and symbol for all that is happening along the border: the supposed chaos, the real desperation and the political crisis that has both bound and distanced the governments of the United States and Mexico.

And so it was on a recent Friday that dozens of journalists, lawyers and aid workers gathered in the concrete plaza just outside the Tijuana crossing, waiting for the latest chapter in the border crisis to unfold.

In an awkwardly coordinated effort, the American and Mexican governments had announced that they would start a “Remain in Mexico” program.

The policy was aimed at forcing asylum seekers to the United States to return to Mexico while they awaited a decision on their application.

The decision was sudden, and for migrants, devastating.

Having endured the trek north, through routes brimming with thieves and smugglers, the migrants found that the road to asylum in the United States would end, for now, in Mexico.

Pedestrians walk up a ramp at El Chaparral border crossing in Tijuana.

The United States applauded what it called a binational effort.

Mexican officials insisted, however, that the plan was forced on them and that they had no say in the matter, but that they would take the asylum seekers back in the spirit of humanitarianism.

Those gathered to respond to the ramifications of the deal — reporters to cover it, along with lawyers and activists to offer counsel and assistance — filled the plaza in tribal clusters and waited for a returnee to pass back through the gates, which would be a repudiation of decades of asylum practices in the United States.

Instead, the only thing that passed through the crowd was rumor.

Someone heard that the first returnee was due at any moment. Within seconds, a line of journalists staged themselves in front of the exit. A family approached, carrying suitcases and small bags. They paused to look at the phalanx of journalists, then passed without a word. They were not the returnees.

As the crowd waited for someone to come back, white vans were lined up in a parking lot, preparing to take another set of migrants across to apply for asylum.

Volunteer aid workers stood pressed against the white metal bars, whispering goodbyes and shedding tears.

They grew hostile as journalists took pictures, with a few of the volunteers shouting at the photographers to stop. These were asylum seekers under threat, the volunteers said, and they could be endangered if their image surfaced in the media.

When that request didn’t work, the volunteers began sticking their hands in front of cameras to block them. A few tugged at camera straps. A Mexican journalist took issue with an American activist.

“I have a right to do this,” he said in Spanish. “I’m following the law, in my country. When I’m in your country, I’ll follow the law there. But don’t tell me how to act in my country.”

Journalists waiting for the arrival of the first group of asylum seekers to be returned to Mexico.

His aggressor recoiled, and then claimed the high ground. She told the crowd she was prepared to make the ultimate sacrifice to save the migrants, who seemed to have no problem at all with the journalists taking pictures and asking questions.

“I’ll take a black eye if I have to,” she announced, although the threat she seemed to be describing wasn’t immediately apparent. “I mean, I don’t want to, but it’s worth it to protect these people.”

The standoff continued for a few more minutes, until the vans had loaded everyone up and driven away.

The knot of journalists and activists loosened, and eventually, with no sign of any returnees, everyone left.

Four days later, the first returnee, a bleary-eyed Honduran man worn from his multiday ordeal, would pass back into Mexico. Upon entry, he was whisked away by Mexican officials before he could be interviewed.

If theatricality has become a reality along the border here, one could argue that Mr. Trump is its full-time producer.

The language of crisis and chaos, however unfounded, has prompted a wave of coverage, especially in the United States.

In Mexico, forcing migrants to wait months to cross and apply for asylum has left thousands in a state of man-made crisis.

Some leave. Others find work in Mexico and wait for better days, or cross illegally elsewhere. A few have attempted to rush the wall, only to be beaten back with tear gas.

Those images can lend credence to the border-as-chaos plotline — that the United States is under threat and that only walls and deterrence can protect it. That anyone, if given the chance, would gladly sneak across to make a new life in the United States.

But where the border comes to its western end, where the wall dives into the Pacific Ocean and its barnacled stanchions split the crashing surf, another image prevails.

A band plays on the beach in Tijuana.

On the United States side, the beach is abandoned, undeveloped, barren. In the distance, San Diego is barely discernible in the evening haze.

The entire beachfront on the Mexico side pulses with life. The portraits of misery and desperation give way to a Friday on the beach in Tijuana.

A child runs in circles on the damp sand, screaming with delight as a small dog chases close behind. A group of hippies dance in a drum circle. Young couples saunter down to the water’s edge to snap selfies in front of the wall.

Music rains down from the short bluffs overhead, as restaurants and bars begin to fill. Families spread blankets on the sand to watch the sunset. Beachfront stands sell sticks of grilled shrimp.

An openness prevails. Amid the cacophony, a brass band begins a set of folk tunes, a sonic dissonance no one seems to mind.

‘Protecting’ a wilderness. Trammeling it, too.

Parker Deighan was one of the activists charged after trying to help migrants crossing a wilderness area in Arizona.

AJO, Ariz. — "A wilderness, in contrast with those areas where man and his works dominate the landscape, is hereby recognized as an area where the earth and its community of life are untrammeled by man, where man himself is a visitor who does not remain."

So begins Section 2 (c) of the Wilderness Act of 1964, a federal law that today protects some 110 million acres of land in the United States.

It is also, today, being used to underpin a criminal complaint that has sent chills through the immigrant rights community.

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Last year, federal prosecutors charged a group of activists with illegally entering the Cabeza Prieta National Wildlife Refuge in southern Arizona, a rugged area that spans some 800,000 acres of sepia-toned desert and pleated mountains along the border with Mexico.

Their crime: entering without permits to leave supplies for migrants crossing into the United States.

Four people from the group, No More Deaths, were convicted this month, and more face trial.

Though not the first time the government has gone after the activists, the breadth of the campaign against them, and the use of the Wilderness Act, appears to be a first.

A border patrol agent at the Cabeza Prieta wilderness refuge.

Ordinarily, people caught wandering the refuge without a permit might be sent off with a warning or perhaps a summons. The Trump administration opted for the most severe approach.

“The cases are on their surface about wilderness, but I think sitting in the courtroom and watching the trial really laid bare the fact that it’s not just about wilderness,” said Parker Deighan, one of the volunteers awaiting trial on a misdemeanor charge in the case. “It is about targeting humanitarian aid and targeting care for folks who cross the border.”

In convicting the activists, a federal judge said their actions had eroded “the national decision to maintain the refuge in its pristine nature.” And “pristine” is a word that could be easily applied to much of the border area. Tracts of ridged desert populated by barrel cactus and giant saguaros that hug the skyline are untouched reservation land for 75 miles of the border.

And yet a wall could be coming. This despite the fact that one already exists.

The government’s action against the activists, whatever the legal merit, raises broader questions along the border, in particular here, where Arizona abuts its Mexican counterpart, Sonora.

Among them: Who exactly owns the land and gets to say what can or cannot be done to it? Who can make permanent man’s touch on the wilderness, and who suffers for it?

The ridged desert is populated by barrel cactus and giant saguaros. Much of it is untouched reservation land.

A short drive from Cabeza Prieta lie lands held by the people of the Tohono O’odham Nation, which the tribe has occupied for centuries. Here, the trammeling of the land has been authored exclusively by the American government in its campaign to seal off the dry edges of the United States.

“It is sort of a contradiction what they are doing here,” Verlon Jose, the Tohono O’odham Nation vice chairman, said on a recent tour through a section of the nearly three million acres granted to the tribe. “No one wants this wall, and they are saying they are going to build it anyways.”

The tribe has occupied the land for thousands of years, since before there were countries to separate with borders. Its land once stretched from central Arizona all the way down to Hermosillo, Mexico, but geopolitics forced a retreat.

Today, the tribe is fighting to preserve what’s left. Mr. Jose and others are in a pitched battle to halt the construction of any more walls on their land, which is a wilderness in all but name, replete with saguaro forests, untamed brush and tracts of desert arroyo and washes that flood every spring.

The wall that exists now is a welded chain of X-barriers that form a straight line across the southern edge of Tohono O’odham land. To the side, a dirt road has been scratched out of the plains.

Verlon Jose, the Tohono O’odham Nation vice chairman, at the existing border barrier.

This was, to many on the reservation, already a sore point.

More than 2,000 members of the tribe are registered in Mexico. Graveyards sit across the fencing in place now, accessible through a few unmanned border gates exclusively for tribe members.

A new wall would upend nature entirely — from the unspoiled views across a landscape indifferent to borders to the animal life whose free passage between sides would end.

“It’s our backyard,” said Mr. Jose. “There’s not just the physical effect of a wall. It’s psychological and emotional as well.”

No wall needed: A shutdown can also bring things to a halt.

The cliffs on either side of the Rio Grande at the Mexico-United States border are mirror images of each other in the Santa Elena Canyon. The Mexican state of Chihuahua is on the left, Texas on the right.

BOQUILLAS DEL CARMEN, Mexico — The land here is indifferent to division, heeding no borders as nature claims both sides in its staggering sweep.

The limestone cliffs soaring 1,500 feet over the banks of the Rio Grande are mirror images of one another on either side of the Texas and Mexico divide. So are the undulating hills that erupt into banded peaks. The waxy scent of creosote is everywhere.

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Still, the idea of the border has come crashing down all the same into the vast territory where Big Bend National Park runs into its Mexican counterparts, forcing both sides to yield to a political reality that trucks little nuance.

In Boquillas del Carmen, a small speck of a town near the Maderas del Carmen park in the state of Coahuila, what tourism there was had come to a grinding halt, collateral damage of the monthlong government shutdown in Washington that just ended. The boats that ferried tourists across the river had stopped. Two restaurants that opened to serve a nascent industry were shuttered, for the moment.

“The shutdown came in our peak season,” said Veronica Ureste, 32, a lifelong resident of Boquillas del Carmen, who sells artisanal products to tourists. She was standing in her kitchen as driving rain pelted her roof and intensified a general feeling of gloom. “We work during this tourist season to survive for the whole year.”

Veronica Ureste, 32, feeds her 3-year-old son, Tadeo Mendoza, next to her sister, Carina Ureste, 26, in the kitchen of their home in Boquillas del Carmen, Mexico.

Survival has been a relatively constant state of being for the people of Boquillas, which is nestled along a low bluff and is five hours from the nearest big town by alternating patches of paved and dirt road.

Until tourism came along following the reopening of the river crossing in recent years, people were abandoning their homes to find opportunities elsewhere.

Across the now-impassable river, Big Bend National Park, which sweeps over the southern edge of Texas to the banks of the Rio Grande, felt similarly forlorn amid a monthlong, partial government shutdown.

Traffic had slowed there, too. Cars seldom pass. Campgrounds sit empty. On the most popular trails, tourists who made plans months earlier trudged through the natural habitat, equally frustrated and thrilled by the solitude.

The nature of the land heeds no borders in Big Bend National Park, which sweeps over the southern edge of Texas to the banks of the Rio Grande.

Phyllis and John Brewster were up early, hiking the Santa Elena Canyon in the sunless morning chill with a handful of other visitors. Mrs. Brewster glanced toward Mexico, and at the sheer rock wall that marked its start.

Not much happening on that side, from what she could see.

“There’s a natural boundary,” said Mrs. Brewster, 76, a retired elementary schoolteacher from Grosse Pointe, Mich., as she made her way up a walkway etched into the cliffs. “What the heck do you need a wall for?”

John and Phyllis Brewster hike the Santa Elena Canyon in the sunless morning chill with a handful of other visitors.

Mr. Brewster, a retired veterinarian and lifelong Republican, stood quietly, staring out over the flood plain and the narrow river at its center.

“The migrants ought to know about this,” he said. “It’s a great place to cross the river.“

Mr. Brewster wasn’t an obvious opponent of the current administration’s border policy. He voted for Donald J. Trump in 2016, a revelation that surprised even his wife. At the time, he said, couldn’t bring himself to go with a Democrat.

Now, more than two years on, the scandals, the nativist language and the vitriol are just too much for him. He said he hated that none of his fellow Republicans seem willing to do anything about it. And he hates what he sees as the demonization of migrants trying to reach the United States.

The boat that is used to ferry American tourists back and forth across the stretch of the Rio Grande between Big Bend National Park in Texas and Boquillas del Carmen, Mexico, floats unused.

And now, here he was, in a nearly empty and unattended national park, bereft of personnel to police the border. Even the weather seemed intransigent — a dense fog refused to lift, practically plugging the canyon shut.

The Brewsters did missionary work in Central America. They knew people there, he said. Good people.

“It’s a travesty to close down a country,” he said, shaking his head slowly. “These people are escaping serious problems for a better life. All of our ancestors were immigrants at one point. To do this is a sinful act.”

A frantic swim, a frigid river: ‘This is how you apply for asylum now.’

An underage asylum seeker is taken into custody by the U.S. border patrol after swimming across the Rio Grande. The bridge connects Eagle Pass, Tex., to Piedras Negras, Mexico.

PIEDRAS NEGRAS, Mexico — Stripped to their underwear, the small group of boys stood shivering on one of the bridge’s footings, pausing in the bitter cold to reconsider their crossing.

They were nearly halfway across the Rio Grande, headed for Eagle Pass, Tex. Their clothes lay in a soggy pile to one side of them, discarded to reduce the drag on their remaining swim to the other side, where United States Customs and Border Protection agents lined the banks of the river waiting for them.

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Border patrol airboats circled nearby, passing beneath the bridge as the boys — most of them teenagers from Honduras — pondered whether to return to the frigid water.

On the Mexican side, people lined the riverfront esplanade to watch, quieted by the spectacle of despair. Locals pressed up against the hand railings to get a better look. So did migrants, who were not crossing with the boys but wished them well.

“This is how you apply for asylum now,” said Oscar Antonio González, a 21-year-old Honduran, bracing against the cold as he watched his countrymen’s trip across the river. He was not going with them. “You can’t make it across any other way.”

Oscar Antonio González watched as teenagers tried to make it across the Rio Grande.

Only one of the boys managed to reach the American side, in a final, frantic paddle. As soon as he reached the bank, he was gathered up by uniformed agents and whisked away in a S.U.V.

The other swimmers gave up, boarded the airboats and were brought back to the banks of Mexico, where they had started and where ambulances now waited.

Before a new border wall became the focal point of a bitter national debate in the United States, and the cause of what is now a monthlong partial government shutdown, most asylum seekers simply crossed the international footbridge that connects Eagle Pass with Piedras Negras. Migrants were allowed to enter, apply for asylum — and then wait for a decision.

Today, border agents operate a checkpoint installed in the center of the bridge, which allows them to turn migrants back before they can enter United States territory.

This leaves migrants with few options.

They can go home, which few do, having come so far already. Or they can look for other ways across, often illegal ones.

Ambulances waited on the Mexican side for some of the boys who didn’t make it across the chilly waters of the river.

Mexico is unsafe almost everywhere it touches the United States, and Piedras Negras, a city of about 165,000 people, is no exception, despite notching some recent improvements in security.

One asylum-seeking family from El Salvador was recently kidnapped here after it was turned away by United States agents, according to statements given to the American Civil Liberties Union. The family was forced to negotiate bribes to Mexican authorities before their release could be secured.

It then took lawyers from the A.C.L.U. accompanying the family members for a second attempt at asylum before they were successful and processed at the port of entry in El Paso, hundreds of miles away.

Most asylum seekers do not have the luxury of legal assistance, subjected to the vagaries of a system unevenly, crudely and sometime cruelly applied. And as the Trump administration turns up the pressure, their desperation has only intensified .

But not their resolve.

The desperation differs from crossing point to crossing point, our journey along the border has found.

In some places, it's overcrowded migrant shelters. At others, its squalid encampments on bridges. Here in Piedras Negras, it’s children screwing up the courage to plunge into the cold water and the swift currents.

And yet the migrants continue arriving at the border every day, some from as far away as Cameroon, traversing half the globe to find a new life in the United States.

Oscar Lopez Elizondo, a former mayor of Piedras Negras, which, despite recent improvements in security, remains unsafe. A migrant family was recently kidnapped here after being turned away for asylum in the United States.

But this part of Mexico is a good reminder that not all border stories run from south to north.

In the town of Múzquiz, a few dozen miles from the border at Piedras Negras, the members of the Kickapoo tribe reside on a reservation granted to them by the Mexican government more than 150 years ago. Fleeing the brutality of American soldiers and marauders of the Old West, the tribes members crossed south into Mexico for safety, where they stayed and preserved their traditions.

“The border protected us,” said Andres Aniko, the spiritual leader of the Kickapoo in the Mexican state of Coahuila. “It stopped the white man from coming over here.”

The Kickapoo enjoy dual citizenship, and are allowed to cross the border without visas, though many are content to remain in Mexico.

“We found peace here,” Mr. Aniko said from the tribe’s reservation, which is largely off limits to outsiders. “It’s one of the reasons we have been able to preserve our traditions. We were isolated here.”

Goods flow freely. People? That’s another story.

Asylum seekers who are waiting for a chance to present their case to American immigration authorities camp out on the bridge connecting Laredo and Nuevo Laredo.

NUEVO LAREDO, Mexico – Thirteen thousand trucks a day. A million dollars a minute.

That, on average, is the value of the cargo that crosses the border between Laredo and Nuevo Laredo on the United States-Mexico border.

Here, between the two Laredos, the border is booming. Trucks loaded with everything from car parts to packaged food hum across a bridge that has been especially designated for commerce, making it the largest land port in the Americas.

“We are the heart of Nafta,” says Edgardo Pedraza, the head of the Customs Brokers Association in Nuevo Laredo, who insists on being called Gary. “I think of the two sides as one Laredo.”

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Gary himself has dual nationality, and is married to an American citizen. His children go to school in the United States, and the family has homes on both sides of the border.

Geographically, the two cities practically run into each other, bisected only by the Rio Grande. Children cross from Mexico to the United States to attend school. Workers cross, too, as do shoppers, who return with outlet mall bags at all hours of the day.

The outlet mall in Laredo, next to the border crossing bridge, seen from Nuevo Laredo.

The two cities share a baseball team, and a history dating back a century and a half. Spanish is spoken on both sides, forging a cultural bond distinct to border towns.

Neither side wants the wall. The river, for most, is border enough.

But even here, there is a stark difference in the freedom of movement of goods versus people.

Every day, hundreds of Mexicans, many with wives and children still living in the United States, are deported and dropped off in Nuevo Laredo.

Migrants who have just been deported to Mexico are welcomed back in an orientation session at the Tamaulipas Institute for Migrants.

“We have grown so much with the United States in terms of trade, commerce and technology,” said José Martín Carmona Flores, the head of the Tamaulipas Institute for Migrants, a state agency tasked with managing the return to Mexico of tens of thousands of migrants. “But we have never really been able to achieve this with the flow of people.”

Mr. Carmona had just finished a welcome session for deported migrants, a class of largely men haggard from spending a varying number of weeks in detention on the American side.

Mr. Carmona spoke to them as a coach might to the players of a losing team. He told them they were special – not just anyone could make the passage north as they had done. They worked harder than most, clocking in 14-hour days in the United States, and Mexico needed them.

“We can’t work like you guys,” he said.

People waiting to apply for asylum stay at this overcrowded migrant shelter for weeks, sometimes months.

“People may look at your tattoos, earrings or the way you walk and wonder what you’re all about,” he added, miming a tough-guy walk that elicited a round of laughter from the men.

“The truth is, you guys are going to replace us, you work harder than we do,” he said. “And we need you. We need you to lift this country up.”

A few faces crumpled, the men caught off guard by the kind words. One man began to weep. Afterward, Mr. Carmona sent them off to grab a meal before their bus trips back home.

“Most of them, when they return, it’s their dignity that’s suffered the most,” he later explained. “Our job is to lift them up and tell them how important they are, to respect the sacrifices they made.”

To help them acclimate, Mr. Carmona called in a pair of executives from a trucking company to register anyone interested in a job. With a nationwide shortfall of more than 200,000 drivers, the company promised good wages, at least by Mexican standards.

Just past the American customs checkpoint on the Texas side, a torpid groan fills the air as tractor-trailers ease past in quick succession, destined for states across America.

Trucks on the Texas side of the border.

Drivers queue on the raised surface of a traffic island, waiting for their rigs to clear the booth and for the start of their shifts.

“We need the U.S. and the U.S. needs us, too,” Jonathan Gamboa, a 29-year-old driver from Mexico, said one recent morning.

Mr. Gamboa accepts his place in the order of things: He has a visa that lets him transit through the United States, but not live there. He could make a good living driving on the American side, but that was it.

“Every day the merchandise crosses and I cross with it,” he said with a shrug. “And I’m O.K. with that. I just can’t live in Texas.”

They were buried without names. Now some, at least, have recovered their identities.

Anthropology students from Texas State University dig trenches in search of unmarked graves at the public cemetery in Falfurrias, Tex.

"The Daily" is sending audio dispatches from this trip. Listen here.

FALFURRIAS, Tex. – It’s about an hour-and-a-half drive from the nearest border crossing to the town of Falfurrias, the seat of Brooks County, Tex.

From the highway, Texas unfurls in wide sheets of scrubland, dense understories of small trees and thorny brush that rise in gnarled stands along the sandy plains. Patches of mesquite, blackbrush and huisache crowd the horizon.

Like the border itself, which lies some 80 miles away, it is an unwelcoming place for migrants.

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More than 700 have perished in transit through Brooks County over the last 15 years, claimed by heat and dehydration while trying to find their way along the parched tracts of ranchland. The real number is surely higher. The local sheriff, Benny Martinez, thinks only one in five is ever found.

Migrants disperse here after crossing into the United States, avoiding a border patrol checkpoint. They trek through the dried-out terrain, seeking shade under the boughs of live oaks. Hunters occasionally stumble across hats, empty water jugs and leathered remains banked against trees.

In spite of the risk, migrants continue to make the journey through the wilds of Brooks County year after year, carried along by hope. And every year, dozens die. No one believes his or her journey will end like this. They can't. Here, the dead do not teach the living.

More than 700 migrants have died passing through Brooks County over the last 15 years, lost among the parched tracts of ranch land.

For years, the remains were conveyed to the county cemetery in Falfurrias, then interred in the open space along its peripheries, often in plots too small or poorly located to sell.

No one is quite sure how many were buried; until 2013, the county kept no records.

But Eddie Canales, the founder of the South Texas Human Rights Center, has forced the remains into the open, hoping to rescue them from anonymity.

Since 2013, anthropologists have been coming with their students to exhume the bodies and extract DNA samples. With no maps or records, they dig narrow trenches guided by the memories of local gravediggers. The samples are then cross-referenced with missing person databases.

Of the more than 150 remains unearthed in this cemetery, 30 have been identified.

“It’s for the families of the missing,” said Kate Spradley, a forensic anthropologist from Texas State University overseeing the effort.

Dr. Spradley stood nearby as a team of students brushed the dirt away from a set of remains buried several feet deep. A worn trash bag, blistered by age, held the bleached bones stacked neatly inside.

A worn trash bag, blistered by time, revealed bleached bones stacked neatly inside.

Above that, packed into the soil, she spotted the faint traces of calcified bone poking through the grit. Another body. That made 16 exhumed in just under a week.

The bodies tell their own stories, Dr. Spradley explained. One man carried photocopied money in his pockets to throw off robbers. Others are buried with stuffed animals. Some are buried clothed; others as skeletons, having died long before they were found.

Each new discovery brings conflicting emotions, a sense of satisfaction tempered by sorrow. She wonders if they will ever find all of the remains.

“You look around and you just think, ‘There’s an open space, there’s an open space,’” she said, scanning the verdant grounds, where fresh cut flowers lay against polished headstones. “And there could be a migrant buried anywhere there.”

She paused for a moment. The sound of shovels striking dirt filled the cemetery.

“I always think, you know, what if one of my family members went to another country and never came back,” she said. “Would anyone pick up the phone to help me? And if they picked up the phone, would they care enough to help me?”

South Texas Human Rights Center staff and volunteers unload trucks after an afternoon spent resupplying water stations.

Few did care here until 2013, when 130 bodies were found -- the largest number the county has ever recorded. It wasn’t that 130 died that year, only that, whether because drought cleared out more brush or out of plain dumb chance, they found that many remains.

That was when Mr. Canales decided to come out of retirement to found the human rights center, after a career as a union organizer. A 70-year-old Texan with an easy laugh, he applied the same principles to human rights as he did to union organizing.

“Developing a connection, basically,” he said, as he drove the public roads that demarcate thousands of acres of ranch land. “And then, you know, I mean, I'm still the same pushy guy.”

Mr. Canales was on his way to replenish water stations that he maintains for migrants passing through. A little more work for him might mean a little less for the gravediggers. The large blue bins sit along the roadside every half-mile or so, and carry up to six gallons of fresh water. He’s planted a flag near most, to help migrants spot them from the brush.

Arianna Mendoza, left, a staff member at the South Texas Human Rights Center, and volunteers Megan Veltri, center, and Laney Feeser, replenish water stations.

Occasionally, people steal the barrels or puncture them to deter migrants. Canales brushes this off. “You gotta be able to laugh,” he said. “It’s the only way to do this work.”

In the borderlands, of course, not everything is dark and serious. People live their lives as they do anywhere. Whatever the broader political debate, to most, this place is just home. And for some, it feels as though politicians who know little about the area are just trying to gain political points.

“There’s certainly no crisis or state of emergency here,” said Phillip Gómez.

Mr. Gómez was seated at the Jalisco Restaurant along the edge of the highway into town. The television was on over the bar, playing the highlights of President Trump’s speech in McAllen, Tex., about an hour and a half drive away.

But no one was paying attention to that. The D.J. was gearing up for karaoke night. Regulars began filing in, introducing themselves to diners as if they owned the place.

Phillip Gómez, right, sits at the bar in Jalisco Restaurant as, on the TV above, a paid commercial promoted Trump’s border wall.

Mr. Gómez, a 64-year-old technician for DirecTV, sported a white handlebar mustache, plaid shirt and cowboy hat with a pair of sunglasses perched on top. He remained seated while he sang a slightly off-tune rendition of “The Chair” by George Strait.

Afterward, he didn’t much care to talk politics, though he allowed that everyone else seemed to want to talk about the border whether they lived there or not.

Then he talked about the border.

He agrees with Mr. Trump, he said, and though he feels bad for migrants fleeing violence, that’s no reason to let everyone just come into the U.S.

“Why do people have walls in their backyard?” he asked, passing off the microphone for the second time that night, after a second George Strait song. “Because they don’t want people in there. There’s no difference. Explain the difference to me.”

Mr. Gómez, who speaks Spanish and whose great-grandparents immigrated from Mexico, doesn’t feel as if the system can bear much more.

“I’m all for helping people,” he said. “But too many people are going to bring down our system.”

The border can be an obsession. Or an afterthought.

There are no fences or border guards where the Rio Grande empties into the Gulf of Mexico, at the eastern endpoint of the border.

BROWNSVILLE — There are no signs, markers or commemorations. Just a languid river passing through, bearing the scent and sediment of its nearly 1,900-mile journey before it expires quietly in the Gulf of Mexico.

A border comes to its end.

NEW MEXICO END Tijuana TEXAS Day 1, Brownsville MEXICO PACIFIC OCEAN CALIF. NEW MEXICO ARIZONA END TEXAS Tijuana MEXICO Day 1, Brownsville PACIFIC OCEAN

There are no fences or border guards, no migrants huddled along its channeled banks. Just a few fishermen on either side casting into the low tide of an early morning, equally stymied by an indifferent catch.

“Nada,” said Juan González of his quarry, echoing the deflated sentiment of his counterparts angling on the American side.

For Mr. González, a gas station attendant from nearby Matamoros, the border was an afterthought.

“I guess from here it’s pretty easy to cross,” said Mr. González, who comes to fish the river’s estuary twice a month and has never made the swim across. Never had any reason to, he said. “Here you don’t have walls and more walls like you do elsewhere.”

As the sun burned away the morning haze, a large white surveillance blimp was visible in the distance.

Migrant men get free haircuts at a shelter near Matamoros, in Mexico by the border with the United States.

For José Jesús Espinoza, who sat at a migrant shelter an hour’s drive away in Matamoros, getting back over the border was all that mattered.

His deportation from the United States earlier this week brought him back to Mexico for the first time in 15 years. The border now bisected his life, with his wife and three children still in North Carolina.

He would cross again, he knew that much. Legally, if possible. If not, given the current impasse over the border and migration, a wall would not stop him.

“We are going to cross one way or another,” he said, offering an incongruous smile. “I mean, we Mexicans have been doing that forever.”

Just over the bridge, in Brownsville, Tex., Narce Gómez sat behind the counter of a hierbería, a store offering tarot card readings, statuettes of saints, herbal remedies and candles.

Narce Gómez offers tarot card readings, herbal remedies and candles at a hierbería in Brownsville. Her clientele is largely Mexican-American.

Her clientele is largely Mexican-American, a population whose predecessors carried their cultures with them across the border generations before.

And perhaps that was the problem. There was a time, more than a decade back, when the lines of customers formed out the door to enter such shops. Nowadays, they are closing, one by one, as interest wanes.