The real reason as to why the south is generally poor is that Reconstruction got cut short due to the North losing patients and interesting in rebuilding the South and the South dragged their feet for another hundred plus years holding back the productivity of black citizens through systemically racist policies. It never was rebuilt after the civil war and you had a significant portion of the population locked out of the economy. The south has through its reputation scared away skilled workers and throwning away decades of economic growth.
Generally, discriminatory policies have negative impacts on economies. Whether they be against LGBT, women, minorities, or immigrants. The most liberal groups in some cities is the Chamber of Commerce as they often are desperately wanting skilled workers to move to the area. I have a friend that is pathologist and there is a very good pathology program in Birmingham, Alabama. They called him up to tell him that he was accepted and he turned it down because he didn't want to live in Birmingham due to its reputation. He could tell by their reaction that they struggle to get people to want to join their program even though it is prestigious.