You are correct. The trains from Philadelphia to Pittsburgh follow the Keystone Corridor. Trackage was originally laid down by a number of railroads including the Philadelphia and Columbia Railroad, the Harrisburg, Portsmouth, Mount Joy and Lancaster Railroad, and others. Then through acquisition it became the Pennsylvania Railroad main line. Then Penn Central, then Conrail, then CSX and Norfolk Southern through various sales, mergers, and breakups. There is freight track running north from Tyrone through Port Matilda which is on the other side of a mountain from State College. Amtrak I guess figured it was not profitable to run a train there so Tyrone to State College is served by and Amtrak Bus line instead.