http://opencarry.com/ <click the state PA>:
Pennsylvania is a traditional open carry state. There are 2 issues that prevent it from being a "Gold Star" open carry state. First, you must have a permit to open carry in the city of Philadelphia and second, you must have a permit to open carry in a vehicle. However, PA recognizes the permits of all 50 states for open/concealed carry in vehicles.
Also, download and read the Pa Gun Rights flyer.
Available here in the Law section
I've OC'd once in the Atown area. I'm about 45 minutes from Atown