Princeton is located between New York and Philadelphia, and is easy to reach by public transportation or by car.
The closest and most conveniently accessed international airport is Newark Liberty International.
The University is easily accessible by train, which runs along the Northeast Corridor line and also stops at the Newark airport. Both Amtrak and NJ TRANSIT trains stop at Princeton Junction, and the south end of campus is a five-minute connecting train ride away.
The detailed travel website of the University gives more information.