Thanks for trying to take my job away from me.
Most of the money my company makes comes from selling wireless systems in South America. Our division is owned by a Canadian company, and they build the hardware in Canada and ship it to So. America. It's designed by folks in the Bay Area.
So if you clowns get your way and lock down America, then there are several hundred of us probably out of a job.
Or I'll have to move to Canada (no thanks).
The Willie Greens of the world can always find isolated examples where it looks like the sky is falling. But overall, and for the long run, anyone with brains is for free trade.
If isolation is such a good idea, then it would be a good idea to practice between the states. Put tarrifs on goods made in Californa and shipped to Michigan. Obviously that's a dumb idea, and it's the same dumb idea when applied across national boundaries.
(Yes, I know the Constitution says only the Congress could do that, but that's not my point)
That right there is a primary reason for the problem. Freetraders have no loyalty to nation or clan. Their flag is the green of money and capital. Capital will go where the profit is greatest and labor is cheapest. There may be a moral imperative to outlaw slavery, but from an economic standpoint slavery is the cheapest labor of all.