FALFURRIAS, Texas - Even if the 3,000 Border Patrol agents in the Rio Grande sector stood 100 meters (109 yards) from each other along the border, the gangs profiting from human trafficking would find a way to get through.
But the agency has to work in shifts, distribute tasks and control hard-to-reach areas along the meandering Rio Grande, Border Patrol spokesman Oscar Saldaña told EFE.
Since Oct. 1, Border Patrol agents in this sector of southeastern Texas have detained more than 132,000 people, an average of 400 a day, surpassing the number of residents in McAllen, Texas.
To enhance surveillance, the Border Patrol uses helicopters, motion sensors, portable turrets and even several balloons that hover over the U.S.-Mexican border with their "eyes" scanning the land day and night.
"Those are some of the most useful tools," Saldaña said at Anzalduas Park, a wetland baked by a relentless sun during most of the day with temperatures in excess of 40 C (104 F).
The main difficulty for Border Patrol agents, many of them of Hispanic descent or who have strong connections to Mexico, is to discern who is an immigrant in distress or a "coyote," as migrant smugglers are known, or a drug trafficker.
"The hardest part in patrolling the border is that you can find yourself confronting dangerous and armed drug smugglers, or you might have to detain children who come through without parents or relatives, and they surrender voluntarily," Saldaña said. "Obviously, the responses are different."
Pointing to the green flowing waters of the Rio Grande, Saldaña said the waterway's peaceful appearance was deceptive and many would-be crossers had drowned tangled up in branches or carried away by strong currents.
Once they reach the U.S. side, migrants, usually guided by coyotes and, sometimes forced to carry drug bundles to pay for their crossing from Mexico, must avoid several lines of surveillance.
Those who are not detained there face an even more dangerous journey 100 kilometers (62 miles) beyond the border when human traffickers abandon them to their fate before reaching Falfurrias, site of one of the Border Patrol's more than 30 interior checkpoints.
This checkpoint, where the staff proudly displays the number of illegal immigrants and pounds of drugs seized so far this year at the entrance, is intended to stop vehicles transporting migrants to Houston.
"Smugglers drop the migrants from cars before reaching Falfurrias and tell them to walk cross country and that, in two or three hours, they will be in Houston," the agent said, adding that the actual distance from here to the metropolis is more than 434 kilometers (270 miles).
This second border strip and the inhospitable territory have made of the Falfurrias' surroundings a death field for unknown numbers of migrants. In 2014 at least 61 people are known to have died there.
The Falfurrias cemetery hides under the ground the consequences of this macabre game of avoiding the Border Patrol to start a new life in the United States.
There, among graves without names, Baylor University researchers have found a ditch where authorities for years have buried the remains of people who died on their journey into the United States.
The bodies could number in the hundreds and the graves are a testament to the dangerous journey Latin Americans undertake to escape poverty.