Pennsylvania has long been a swing state mainly because of the stark differences between the urban centers and the rural middle. Long known for its industrial past, the Pennsylvania of today is much different. It's three largest cities tell the tale.
Philadelphia has long been part of the East Coast metro core that runs from DC to Boston. It sometimes gets lost between its noisy neighbors to the north and south, but that seems to suit Philadelphia just fine.
Allentown and Pittsburgh share an industrial history both based on coal and steel. However, post the deindustrialization of the late 20th century, each has emerged as a player in the information age. Pittsburgh is more advanced, but Allentown continues to make great strides.