OBVIOUSLY a border wall will greatly reduce the amount of foot traffic across the border, and make those who do cross over it easier to track and catch because it will greatly slow them down. obviously the wall would need border patrol and technology too. with no wall people can and will just run right through.
the thing that is all the craze amongst liberals is simply to state that most illegal immigration comes from places other than illegal crossing, although they usually just ignore that that doesn't mean we can't greatly limit the illegal crossings too. liberals say we can use alternative methods to a wall, although they ignore none of the alternatives can do what a simple wall would do- limit people from just running across.
Here is an unintentionally funny article from a Harvard halfwit who is doing his best to say that border walls don’t work, while describing how well they work.