The idea of building a big wall around the United States is a divisive one, with people across the political spectrum arguing that the wall will somehow hinder the flow of people and goods across the border.
But the biggest barrier to the wall is that it’s impossible to erect.
No one has ever built one.
As a rule, building a large wall is a political and logistical impossibility.
When the Mexican government first began constructing a large, artificial barrier in the 1960s, the U.S. military would not let it be done, and the U-2 spy plane that was used to film the process was destroyed.
In response, the Trump administration has refused to permit any U.N. border wall, with the Trump White House insisting that it will not build any large walls in the U