Easy. The coal mining industry could have continued existing for another thirty years, bringing huge losses each year, subsidized by the taxpayer. Like, say, in Poland, which is where you get your cheap labor from, and not the other way around, and the two facts are not entirely unrelated.
It was just the way of the future - the Southeast had lower labor costs, lower cost of land, and advantageous shipping arrangements. The cities just couldn't keep up, and they fell by the wayside.
And yes, it's pretty crappy to go to these cities and tell the people who are struggling there that their businesses deserved to go bankrupt or leave, but there's no other way to do it. The alternative is to subsidize them, and that ends up discouraging progress and also creating a culture of dependence on the government. After all, why invent new stuff if the government will increase the subsidy to keep up with your new manufacturing process?
Letting the free market purge badly competing industry is good for the country and also good for everyone in the long term.