What is the Pennsylvania lines

It was part of the Pennsylvania Railroad Company.  This is a quote from a post by Chris Baer I copied many years ago: "Prior to 1920, all of what were called the "Pennsylvania Lines West of Pittsburgh and Erie" were operated by a separate organization, that was actually an amalgam of the Pennsylvania Company, a holding company for the lines between Pittsburgh, Erie, Cleveland, Ashtabula and Chicago, and the PCC&St. Louis, which controlled the lines to Cincinnati, Indianapolis and the Bradford-Chicago line. plus at a later date the Vandalia system. These companies were managed by a separate "Lines West" organization, which only had the president in common with "Lines East". This organization used the service mark or trade name, "Pennsylvania Lines" as a contraction of "Pennsylvania Lines West of Pittsburgh and Erie." It owned its own equipment, which was so marked, as opposed to Lines East, which was marked "Pennsylvania Railroad" or "PRR".  "Pennsylvania System" was the service mark or trade name used to designate the combination of Lines East and West. You will find it on certain types of advertising matter, and in the names of several joint bodies that had members from both halves of the railroad. The "Lines West" organization was abolished in 1920, although it took about two more years before all of the properties were actually leased to the PRR. At that time "Pennsylvania Railroad" replaced "Pennsylvania System" as the service mark or trade name for the whole railroad. This is what you see on post-1920 timetables, advertisements."  

Anyway, the name "Pennsylvania Lines" went away in 1920 and all Pennsylvania Railroad equipment got "Pennsylvania".  So if you model the WWI era or earlier and the Pennsylvania west of Pittsburgh and Erie, "Pennsylvania Lines" is what you want.