The part I don't get is why is it such a great idea to have trade protections around the US border, but not between the States of the Union? If trade freedom is good between the states, then obviously it's good between countries.
I guess if someone just hates people from other countries, and wishes them harm, then it might be a good idea. But if "our" country is more expensive at some particular work than another one is, then its our fault. Not the other countries fault.
I don't believe in trade unions using coersion to artificially get higher wages. And I don't believe in trade protectionism doing the same thing.