Americans who live near border say Trump's wall is unwelcome

Erecting a concrete barrier across the entire 1,954-mile frontier with Mexico, they know, collides head-on with multiple realities: the geology of the river valley, fierce local resistance and the immense cost.

An electronically fortified "virtual wall" with surveillance technology that includes night-and-day video cameras, tethered observation balloons and high-flying drones makes a lot more sense to people here.

"The wall might make mid-America feel safer, but for those of us that live on the border, it's not making us feel any safer when we know that people can go over it, around it, under it and through it," said Monica Weisberg-Stewart, security expert for the Texas Border Coalition, a consortium of regional leaders.

Rural ranchers worried about drug traffickers and other criminals are less likely to benefit from border walls and fences than city-dwellers, said Adam Isacson, a security expert with the nonprofit advocacy group Washington Office on Latin America.

[...] cross-border trade has been booming.

The region bears the usual hallmarks of American prosperity: strip malls, well-maintained interstates, prosperous gated communities with hacienda-style McMansions.

The Border Patrol's buildup after 9-11 is one reason, argues David Aguilar, who was named to the agency's top job in 2004 by a fellow Texan, then-President George W. Bush, and is now a private consultant.

[...] the number of agents has climbed from 9,500 on the southwest border to 17,500 in 2015.

Many analysts believe the Great Recession was a bigger factor than Border Patrol enforcement in making the U.S. less attractive to Mexican migrants in particular.

Since tower-mounted video surveillance cameras began going up in 1999 in the Brownsville area, illegal cross-border traffic in the area "dried up by 85 to 90 percent," said Johnny Meadors, the sector's assistant chief for technology.

Seventy-two more of the towers, which are 80 to 120 feet tall, are to be installed in the valley by 2021, and could include motion sensors and laser pointers, Meadors said.

Since 2013, the Border Patrol has also had five blimp-like aerostats that float from 1,000 to 5,000 feet above the valley on tethers.

An average of 350 migrants, some adults wearing ankle monitors, now arrive daily at the Sacred Heart parish community center in the border city of McAllen, up from 100 a day in August, said Gaby Lopez, a volunteer at the makeshift shelter that opened in June 2014.