LMAO! Dream on. Anyone can, at anytime slip across the Canadian border, along either coast, and Mexico. Are you going to wall off the entire country? One big prison complex? Put a roof over it and call it an insane asylum.
One doesn't even have to crawl through mosquito infested bogs, and forrest choked thickets to cross the border. just wait for the border guards to go home at some locations, and drive over the rubber cones they put on the road.
The answer is as mentioned above, we must fight this war over there, but we have to have the will to do it, which as we can see just isn't there. Maybe it will be there after we take a few hits, and quit trying to fight a PC war.
Either spend the money for physical border barriers and more patrol personnel, or just 'French yourself' to the enemy over the problem.
I see no problems with the US suspending all foreign aid until the barriers and personnel are in place and diverting that money to a more worthy cause.