Turns out that coal-fired power plants are just not very efficient - only 35% efficiency - so they lose out to all other types of power over the vast majority of the US.
Especially the midwest.
This interactive map allows you to make your own calculations for your area, and figure out what kind of power makes sense for you and your neighbors. (And then repeat that process anywhere else on the map, too.)
Boilers are like 35% efficient. Coal is just the fuel. I know just enough to say almost but not quite the right thing. I think I'm thinking of the Carnot efficiency limit discussed on the Wikipedia Rankine cycle page.
Coal plants (really pretty much any utility scale plant) will assume a 40 year life with lifespan extensions beyond that. People would happy build coal-fired plants if they thought they would remain profitable for 40 years. But the regulatory uncertainty means there's a really good chance they won't be.