I was about to mention coal, but then I found this map:
Oddly enough, the coalfields in PA are mostly confined to the western portion of the state, and cover less than half of the state overall, so energy/environmental issues likely don't have a large impact on the voting patterns of central PA the way they do in other coal states.
which is why western PA historically supported Democrats up until recently. It votes kind of like West Virginia and is prone to the same political trends.
There doesn't appear to be any kind of coal industry in central PA which explains why it has been more historically Republican.
No, but the people who took the coal and made it into things like iron and steel were located in central and eastern Pennsylvania. So you had steelworkers in what was up until the early 20th century a very anti-labor environment and may have been more inclined to vote Republican as a result; and all of the engineers, managers, factory owners, bankers and lawyers working in the steel industry who were voting Republican out of self-interest.
