USA is not some nation that is trying some one race thing, they are filled with a million different races, people from all over the world go there. The logical differences is that USA is a place that accepts immigrants, in fact, every single year there are green card drawings that end up taking a certain amount of people (in thousands) to go live there if they want to, and that is the difference in the south of the wall understanding.

Instead of building a wall to keep people away, they could just put in entry points where you get the information of those people, put them in places like true immigrants, and make them live the USA life. I have a friend who did that to Netherlands, and immigrated, and it wasn't anything like this. Why try to build a wall, when you can build a door?