on Farming and Manufacturing in the South

You  can thank/blame better farming equipment for the conditions that led to "Right to Work" laws in the South:

Agricultural productivity pushed millions of farm workers off their land and created a large pool of poor, jobless workers. Finding employment for those workers became a high priority for southern politicians, many of which underwent a dramatic political transformation -- from a focus on protecting southern culture from the federal government, to aggressively recruiting new enterprises from the industrial portions of the country. State leaders began to wave generous incentive packages at northern firms, including tax breaks and right-to-work laws, in order to attract production facilities. And many were successful; industrial employment rose sharply across the south, turning the southern Piedmont into the country's second industrial heartland. 

That is from Ryan Avent's book The Gated City.


All of this makes sense; a large pool of labor puts pressure on politicians who, to save their own jobs, bend over backwards to entice business to their states. Which in turn hurts labors position in said states. A sacrifice locals don't mind because having a low paying non-union job is better than not having a job at all, but to workers in the midwest it was a death sentence. A well played game by management.