At the rate things are going, if a wall ever gets put up at the border, it’s becoming more and more likely it’ll be aimed at keeping people in, not keeping people out:

State Department Hikes Fee To Renounce Citizenship Amid Record Number Of Renunciations

The only bright spot in there is that we only need to look at the Berlin Wall (what’s left of it, anyway) to know how that’ll likely work out over the long run.