Trump promised us a wall, and he knows how important it is to keep voters motivated. DHS wants the wall. In video clips we see how it does stop all but the most athletic climbers. If you saw the 6,000 member caravans going to Tijuana to get into the US any way they can, you'd know that the new wall is really needed. We can't afford open borders.
Ain't gonna stop athletic tunnelers and swimmers.
The coyotes who help migrants cross into remote areas of Arizona and Texas will starting charging $5000 to go through a tunnel instead of crossing a desert. And the the drug cartels will build the tunnels because they need them to move drugs into the U.S.
A better solution would be something along the lines of the Marshall Plan: Instead of spending billions to build "steel slats" as Duh Donald now calls it, use the money to get crime and the cartels under control IN country, in Central America. Fucking A, if we can invade Iraq and Afghanistan, we can sure as hell send troops into Honduras and Guatemala and help the people of those countries STAY home instead of fleeing crime and coercion and worse.