Unfortunately, an EO won’t build even one.
Laws.
Congressional allocations.
Supreme Court decisions.
This lays the groundwork to relitigate those 60’s and 70’s era court decisions that contributed so much to this mess.
Back then, there wasn’t much if any data to show that institutionalization was better than not committing people. Now we do.
It would be much easier to put a wall around Democrat cities such as New York City.

Another EO requiring legislation and appropriation — that Trump will never get unless he focuses on the midterms rather than Greenland.