If a state’s borders aren’t enforced, either those borders are not in fact the state’s real borders, or the people residing within those “borders” are living in a failed state.
And as I said before, the southern border is mostly made up. People crossed it for thousands of years without some crappy wall in the way. They will continue to cross it even with a wall.
What are you in favor of, then?
A border wall is an ecological tragedy.