Slavery used to be practiced throughout the United States, eventually falling out a favor in the Northeast but not in the South. Segregation was a British practice, it has why it was seen in British colonies throughout the world. In fact the name Wales is derived from an old Anglo word meaning foreigner. So yes, the major indigenous population of Britain, the Britons, were called foreigners by their Anglo-Saxon invaders. For the last 2,000 years. Apartheid that everybody decried in South Africa? That started when it was still a British colony. India may have its Untouchables caste, but as far as their British overlords were concerned, all Indians were untouchables while they were British subjects. Segregation finally ended in North America in 1985, when it was outlawed in New Brunswick. That's in Canada, btw.
So basically the Northeast fought against slavery during the Civil War, just like it basically fought the Revolutionary War, just like it basically fought World War I & II and so on and so forth, and yes, rebuilt the South by modernizing it and taking it out of the Third World with the New Deal and a society that was greater than dirt roads, candles, and lynchings of anybody who wasn't a Protestant Anglo whenever they felt like it. My gosh, the selfies they took back then. Ugh, unimaginable to the civilized North.
I can see why people would oppose such socialism because we should have left them as they were. Still an economic drain as they had been since British Colonial days.
So yes, you have the Northeast to thank/blame for bringing the South and the rest of the planet into the modern era. We literally recreated the world in our own image. Goodness gracious, Southerners from politicians to those in Hollywood to country musicians, of all things, take courses to erase their accents. That's how embarrassed they are and wish they were us. That says a whole lot.
People mocking Europeans for dying in this heat wave, can you imagine how it would be in the South of right now today if it wasn't for FDR's Communist TVA?
We should have left them as they were. Trump could have them.