So where did Schuylkill's Republicanism come from?
It is mostly white German and Welsh stock (initially with Pennsylvania Dutch settlements, and then came the mill workers and miners (a lot of whom were Scot-Irish, and the Welsh RR workers have been GOP since rocks cooled). Now the mining and mills are mostly gone, replaced by a bunch of outlet stores in Pottsville. So, what used to be marginal politically territory, has given the demographics (Catholic Germans have joined their Lutheran cousins as a heavily GOP leaning group now), moved towards the GOP, attended by huge population loses, as the issue of the miners and mill workers get the hell out of Dodge.