In interviews with The Associated Press, they described how erecting a concrete barrier across the entire 1,954-mile frontier with Mexico collides head-on with the geology of the Rio Grande valley, fierce local resistance and the immense cost.

That's why an electronically fortified "virtual wall" with surveillance cameras, observation balloons and drones makes a lot more sense to people. 

The locals are not convinced that a 30- to 40-foot concrete wall will cure the nation's immigration ills. Few were surprised when the president-elect seemed to soften his position after the election, saying that the wall could include some fencing.