MISSION, Texas — The influx of migrants crossing the U.S.-Mexico border has grown so large that it now requires its own transportation system: government buses that spend each night idling on a Texas roadside, awaiting the latest arrivals.
The buses, joined by a fleet of Border Patrol vans, illustrate the immense and grindingly routine task facing Border Patrol agents in the 5-mile slice of deep South Texas that has become the epicenter of the recent surge in illegal immigration.
An Associated Press reporter recently spent several days in this arid terrain, revealing a daily tide of migration that sends impoverished families into a harsh landscape bristling with cameras, lookout towers and heavily armed patrols. Against that backdrop, human smugglers and drug cartels match wits with overwhelmed American authorities.
Deputy Rudy Trevino was patrolling a park along the border when he spied movement in the darkness. Swinging his spotlight toward the motion revealed 14 women and children who had just sneaked across the Rio Grande in a small boat.
The youngest, a 14-month-old boy from Guatemala, lay quietly in a baby carrier hung from his mother's chest. The oldest, a 38-year-old woman from El Salvador, cried with her head in her hands, her 7-year-old daughter leaning against her.
Most of the immigrants hail from Central America, and many come with children. They often turn themselves over to authorities immediately after crossing the river, following the advice of smugglers, friends and relatives, who tell them they will eventually be released and allowed to continue to their destination.
For parents with young children, that has largely been true because the U.S. has only one long-term family detention facility, in Pennsylvania, and it's full. Most parents are handed notices to appear at the immigration office closest to their destination and dropped off at bus stations across the Southwest.
Children arriving without their parents are transferred to custody of the Health and Human Services Department, which tries to reunite them with family members in the U.S.
Both groups have often been allowed to remain in the U.S. while their immigration cases move forward, a process that can sometimes take years.
Migrants' willingness to surrender to authorities has created a system in which smugglers need only to get their human cargo to the American side of the river, rather than guiding them to a populated area.
Just since October, the Border Patrol's Rio Grande Valley sector has made more than 194,000 arrests, nearly triple that of any other sector. In the first week of June alone, agents in this area south of Mission arrested more than 2,800 people, most from Honduras, Guatemala and El Salvador, making it the highest-volume arrest zone on the entire U.S. border. More than 60 percent were children.
The zone is patrolled by no fewer than six local, state and federal law-enforcement agencies, including gunboats crewed by Texas state troopers with night-vision goggles and the Border Patrol's white and green trucks. Helicopters swoop above the winding waterway.
But there's little cat-and-mouse pursuit. Every day, hundreds of immigrants walk up to agents, wave to their remote cameras or simply wait to be picked up on the side of a road like Trevino's group in the park.
When Anzalduas Park is busy on weekend afternoons, it takes only seconds for a watercraft to dart across the river and deposit three or four people onto U.S. soil. From there, they blend into the crowd of park goers.
Trevino said the past two months have been "chaos." He's corralled 100 people in a night and had a group of 50 walk up to him at the park bathroom.
Downriver from the park, the landscape reverts to a band of thick mesquite and underbrush along the Rio Grande. It can feel remote, but it's just a thin buffer between the more than 600,000 residents of Reynosa, Mexico, and a master-planned community in Mission with more than 1,900 homes just a couple of miles to the north.
Across the river is a garbage dump and a Reynosa slum that reaches nearly to the bank. Smoke from burning garbage sometimes drifts across the river so thick it's difficult to see. At the river's edge, discarded pieces of clothing, orange life vests and deflated inner tubes litter the sand.
A few days earlier, as a reporter in a kayak approached a hairpin bend in the river, a cartel sentry on a bluff 20 feet above the river slammed a magazine into his assault rifle. He asked where the paddler had come from and who gave him permission to be there. A radio squawked at his waist. The cartel controls what crosses the river.
That's part of why Napoleon Garza doesn't bring his kids here to fish like he did as a child. Garza recently drove through one of the many gaps in the border wall to cut a tree stump from property owned by his uncle.
"When they built the border wall, everything ended because they left a big old gap right here that so happened to be where our land is," said Garza, 38, who sells firewood for a living. "That's where these guys have to run their dope. It's really sad."
As Garza stood above the river, two Texas game warden boats sped by, each with a rifleman scanning the shores. A few minutes later, twigs cracked and a green-clad Border Patrol agent emerged from the brush checking to see what Garza was up to — a constant occurrence near the river.
The city of McAllen, which draws its water from the Rio Grande, has pumps on a narrow strip of land between the border fence and the river. Workers there started carrying handguns after they came under fire.
The water district installed street lights, erected camera-topped towers and built a road and concrete pad so the Border Patrol could erect a mobile surveillance tower.
The district's president and general manager, Othal Brand, farmed the area for 25 years with his father. There was illegal activity then, too, and it seems likely to continue unless the Border Patrol stations agents every few hundred feet along the river, he said.
"It's like a bad neighborhood," Brand said. "You get acclimated. You don't like it, but you understand it."