Americans may want to think about too many walls and/or fences going up around the nation..
They might need to find a way out some day and run into a wall/fence.
Walls/fences are designed to do two things:
Keep things out and/or Keep things in..
Are you quoting Ron here?
Well, you could put in turnstiles, that would keep the bad guys from coming in, but let anyone make an exit.