They stopped it for a little while because out of state people were getting through. They have re-vamped it and allow you to join through PRPS again only if you carry a PA i.d. It's actually an option when you apply:

"I would like to join Pennsylvania Recreation & Parks Society Incorporated (PRPS) to receive their benefits and to be eligible to join PSECU. The PRPS Friend membership dues are $20. I authorize PSECU to collect and forward $10 from me to PRPS. PSECU will match with another $10 to pay the total Friend membership dues. In addition, I authorize PSECU to send my name, address, e-mail address and phone number to PRPS. To learn more about PRPS, visit prps.org. Please note: A PRPS member who wishes to join PSECU must be a permanent Pennsylvania resident."