He'd build it with guided tours, a golf course and guest amenities on the U.S. side — LOL. But seriously, it really would take immense power and cooperation from our behemoth gubmit establishment to get it done. That may be why he believes it can only be done from the top down.
This is not a premature endorsement of DT by me; just an observation of what it would take to get it built — a massive concerted effort of many federal and state agencies, either to cooperate or get out of the way. As opposed to what has happened to the pipeline, or desalinization plants for California, or north shore drilling, etc etc. Envirowackos alone would find some endangered species of chupacabra to prevent laying the first stone of a wall.
No, probably on both sides!