Case in point . . . many of these jobs in the textile industry in places like the Carolinas and Georgia are jobs that moved there decades ago -- after leaving places like New England and upstate New York. I wasn't around back then, but I'm sure you didn't hear too complaints at that time about a "giant sucking sound" coming from the Old Confederacy.
What has really changed for the South over time is that it simply does not have the same comparative cost advantages that it used to have in comparison to the Northeast. There are still some advantages, but not enough to help the region serve as a major manufacturing center for this country's big consumer markets.
The issue is extremely complex, but it comes down to a very basic economic reality: There is an enormous difference between what people are willing to pay for a product or service and what they would charge to do it themselves -- and this difference is what drives our individual buying habits and national trade policy.
I'll make it a little simpler then. New England and the Southeast are both within the US. They are our people.
South Korea, China, Mexico, Peru, etc. are outside the US. They are not our people.
Our people are to get preferences by us over their people, because they are our people and no other reason is needed. That's how simple it is.