Sealing could be done day one or day two of a new president taking office.
You could immediately have troops or Guard members start patrolling the borders; and seal it tightly and quickly.
No administration has done this (recently anyway); there is reason.
Very skeptical anyone would actually do this fairly simple thing.
Well the political class are puppets, craven, and stupid is why things don’t get done in DC. Most of the law already supports Trump if not all of it.
Romney was right about several things and self-deport is one of them. Once the word spreads that serious enforcement is coming, there will be a mass exodus. Although I imagine an awful lot will try heading north, it’ll be interesting to see what Canada does.
You are correct and it would be easy and quick if someone wanted it done.