In 1955 Soviet Union was already built. The peak of Soviet period is 1965, which is pretty close.
In Europe, most of towns are historic, they're in good places and can take any place in economic system.
In America, there are towns dedicated to mining or specialized farming (rubber?), but they quickly get abandoned when mine is exhausted or the output is no longer needed.
Soviet Union built quite a few towns in remote northern locations, they were way bigger than feasible for mining - like a general purpose settlement. Guess what, now it's hard to rationalize their existence, but people are stuck there and see it as their home. People aren't very mobile in Russia.
I imagine even when diamond mining is over we're going to pretend that this is just another town that can get jobs on its own and it will be held afloat by redistribution. It's going to be pretty miserable place for sure, I imagine.
The conflict in Donbass also has a similar interpretation: coal production there peaked in the late 70 and by the 90 it was an endlessly subsidized rust belt, with a significant minority of the population being born outside Ukraine. It is a backwater hopelessly reliant on outside help, with widespread violent crime, alcoholism, drug use and corruption. It is these rust belts that lower the statistics for the whole Eastern Europe. Young people were leaving it in droves long before the current conflict began.
The disruption by current separatist governments (commanded and supplied by the Russian Federation) have made the decay much quicker - around half the population has left, with a big part of the people remaining being seniors who cross checkpoints to collect their pensions.
BTW, Russia reformed their coal production by closing unprofitable mines and selling the rest. Now producing more coal for less money without subsidies. Ukraine did not and largely kept Soviet mine system intact.
> backwater hopelessly reliant on outside help, with widespread violent crime, alcoholism, drug use and corruption
You have combined "basket of deplorables" reasoning with divisive Ukrainian nationalism to achieve a new low.
You may think it's a backwater but people actually live and work there.
It is largely a statistical illusion - a huge part of Ukrainian economy is in the gray sector. However government transfers, budget spending and industry does show up in statistics.
The two Donbass oblasts actually scored high on GDP per capita, but had much lower quality of life indicators. A large reason for this disparity in income is government transfers, like the big pension and health benefits provided to mine workers. You also had huge indirect transfers like the government propping up failing enterprises and buying production from the regions industrial oligarchs.
A lot has been made about how these people feeling left behind relative to prosperous coastal cities enabled a Trump victory. The trends are of course much older than that.
Anyway, I guess Pennsylvania is habitable when the push comes to shove. Vorkuta, Mirny or Norilsk simply aren't. They're more like Mars bases.
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.