The line that I heard is that they're getting priced out of the New York region and start moving 2-3 hours west. Adjusted for inflation, they probably make a lot less money than a coal worker did there in the 20th century. I'm not sure the numbers are really as high as the outrage from the "older" population either.
Also, in terms of "Pennsylvania being livable", careful about painting the whole of Pennsylvania with a wide brush. There's an old like about Pennsylvania: it's Philadelphia and Pittsburgh with Alabama in the middle.
