Page "New York Tunnel Extension" Paragraph 11

The North River Tunnels carried PRR trains under the Hudson ; for some years PRR electric engines also pulled Lehigh Valley Railroad or Baltimore and Ohio Railroad trains to New York.

The East River Tunnels carried LIRR and ( after 1917 ) New Haven trains, along with PRR trains to the Sunnyside Yard in Queens.

All trains were powered by DC third rail until the 1930s, the same third rail system that still powers LIRR trains.

In New Jersey the third rail ended at Manhattan Transfer, where all trains stopped to change between steam and electric engines.