There are 3 ways to get from T-1 to T-3:

1. Shuttle van service which operates inside the security zone. From the T-3 terminal you can pick it up at Gate 71-A (located just after the check point and Yankee Restaurant) or at Gate 87-A. The only elevator access is at Gate 87-A. From T-1 to T-3: look for signs in the gate area. Van service stops at 11pm.

2. AirTrain is the tram the runs around the airport and rental car terminal. This is pre-security and operates 24 hours.

3. You can walk.