Donald Trump has made his hardline stance on illegal immigration from Mexico the cornerstone of his bid for the White House, calling for a border wall to keep undocumented migrants at bay. However, technology and greater manpower appear to be effectively curbing the number of illegal immigrants slipping through the frontline of America’s southern border.

In Nogales, Ariz., U.S. Customs and Border Protection Agent John Lawson spots a group of men surveying the border through binoculars and talking on cell phones on the Mexican side. Their elevated position provides a clear view of the U.S. agent’s patrol route along the fence, perfect for tipping off groups of illegal migrants waiting in the brush-covered terrain below.

“They’re going to call them when they think the coast is clear to come up to the fence and get over it,” Lawson told CTV’s Richard Madan, who got a first-hand look at border patrol operations in the area.

Much of the border has some type of barrier in place, but it is wide open in some remote areas. In Nogales, home to the second-largest border patrol station in the U.S., an 18-foot tall steel barred fence divides the neighbouring nations.

“In the Nogales area, we’re catching 30 to 40 people on a daily basis,” said Lawson. “It’s a low number compared to what it used to be in 2008.”

Last year, Customs and Border Protection (CBP) caught more than 300,000 people trying to illegally cross the border. That’s down from a peak of 1.6 million caught in the mid-1980s.

Data from the Pew Research Center shows the unauthorized immigrant population in the U.S. has stabilized since 2009, and the total number from Mexico has continued to shrink, now more than one million below its 2007 peak.

“We have the advantage of time,” said Lawson. “If they are going to walk for a day or so to get to where they are going out here, that gives us a whole day to detect them and go after them.”

Lawson and his fellow agents also have the advantage of a US$13 billion budget to bankroll their operations. CBP is the largest law enforcement agency in the U.S., with a staff of more than 60,000 – far surpassing large police forces like the NYPD.

The agency employs a combination of a boots on the ground and high-tech surveillance equipment – including radar, day and night cameras, and unmanned aircraft – to keep an eye on the rugged terrain along the border.

The agency’s mandate includes “protecting the public from dangerous people and materials” and “enhancing the nation’s global economic competitiveness by enabling legitimate trade and travel.”

On a typical day, CBP says it arrests 23 wanted criminals and refuses 367 inadmissible persons at U.S. ports of entry. Over 9,000 pounds of drugs are seized, and 600 individuals with suspected national security concerns are identified.

Still, some near the border with Mexico believe the agency could be doing more. Jim Chilton’s ranch in Arivaca, Ariz. is about 30 kilometers away from Mexican soil. He says illegal immigrants are literally walking through his backyard.

His proof includes surveillance video footage and a collection of dozens of pairs of homemade footwear made from scraps of carpet and other fabric used by migrants to conceal their tracks from law enforcement.

“I was saying you need a wall along the international boundary long before Trump said he was running for president,” he said. “It would help immensely.”

Lawson refused to weigh in on Trump’s construction ambitions.

“(I) can’t answer that question. That gets into the political realm. I just can’t go there.”

With a report from CTV’s Richard Madan

Arizona border