Where in Pennsylvania are you going? There is a SEPTA (Philladelphia area transit) train from Trenton that makes stops along the way to Center City Philadelphia. NJ Transit or Amtrak (faster) from Penn Station will take you to Trenton. Amtrak will take you to Philadelphia 30th St. Station. To get to Penn Station from JFK you can take the NYAS bus from your terminal or take Airtrain from your terminal to Jamaica Station and transfer to E subway or LIRR (faster) to Penn Station.
Where in Pennsylvania are