The Northeast Corridor Line is a commuter rail service operated by NJ Transit between the Trenton Transit Center and New York Penn Station on Amtrak's Northeast Corridor in the United States. The service is the successor to Pennsylvania Railroad commuter trains between Trenton and New York, and is NJ Transit's busiest commuter rail service. After arrival at New York Penn Station, some trains load passengers and return to New Jersey, while others continue east to Sunnyside Yard for storage. Most servicing is done at the Morrisville Yard, at the west end of the line. The Northeast Corridor Line is colored red on NJ Transit system maps and its symbol is the State House. The Princeton Branch is a shuttle service connecting to the line. Connecting SEPTA Trenton Line service between Philadelphia