I was born across the river in NY, lived in Pike county my first year on this earth, grew up in W-B/Scranton, left for a couple of years (Navy) but came back to find that NEPA was a grossly depressed area so I went to Penn State Main, met a girl from Pittsburgh, moved in with her in King of Prussia after graduation for a couple of years before we moved her home to da Burgh about 25 years ago. Here's my take on things:

1: more people live east of the Susquehannah but I-476 is kind of the real line where population density is.

2: Even though I'm about 30 miles from Ohio and on the other side of the eastern continental divide I still think of myself as a northeasterner. I don't really see a midwest attitude because the geography is still pretty mountainous. If anything, I think Pittsburghers sort of identify more with West Virginia.

3: I never really felt connected with others when in Philly but my take was that they really didn't think about Pittsburgh or anybody else for that matter. Pittsburghers OTOH call outsides "jagoffs" and it seems to really stick when they come here to visit. It takes a good 6 months to learn the lay of the land.

4: Though I spent a lot of time as a kid in Scranton (my dad's family is from near there) Lancaster wasn't really thought of. In PA, people tend to stay in their own areas and if you're not in trucking or sending a kid away to school and have to go through Lancaster you don't really deal with it. FWIW I went to school at PSU with kids from Lancaster and they told me that the Amish kept to themselves but would hog the roads and that racism was still a thing. Now I suppose it's more out there.

5: As for Somerset and Erie, again two distant spots on the map. Somerset is basically a truck stop off the Turnpike from my perspective and even though we know people in Erie, it's more an eastern suburb of Cleveland and a pit stop for a trip to Buffalo and the Finger Lakes.

FWIW no matter where you go in PA, if you cross the line into another state the roads get instantly better - except for the WV panhandle.