It's mostly a cost thing, in reality. Closing the Southern border -- "building a wall" if you will -- is an absolutely gargantuan task. The border is huge, many

It's mostly a cost thing, in reality. Closing the Southern border -- "building a wall" if you will -- is an absolutely gargantuan task. The border is huge, many parts it extremely harsh and remote terrain unfriendly to construction projects. Trump made it a huge part of his platform, had a majority, and in four years got a pitiful amount of wall actually built.