Zoo Junction

[1] In 1870, the Pennsylvania Railroad built the Connecting Railway from Frankford Junction to Zoo to bypass congested street running in Philadelphia.

[2] Instead of reaching the city directly from the north, the Connecting Railway turned west, crossed the Schuylkill River on the Connecting Railway Bridge (a stone arch viaduct) and then turned south to join the PRR's Main Line at Mantua Junction.

In 1910, the PRR built two duck-under tunnels to allow trains to reach the Connecting Railway without blocking the Main Line and 37th Street Yard.

The eastern 36th Street Tunnel also allowed grade-separated access to the Junction Railroad connecting to the Philadelphia and Reading Railway.

The western tunnel, called the New York-Pittsburgh Subway, allowed trains running from New York City to Pittsburgh and west to bypass Broad Street station.

Map of Zoo Junction and the multiple lines and services passing through the junction
A 1977 photo of Zoo Junction with the Northeast Corridor visible on the right, the Schuylkill River in the background, and the Philadelphia Zoo on the right.
The south portal of the 36th Street Tunnel used by SEPTA Regional Rail , where two connecting tracks from 30th Street Station 's upper level run under the Keystone Corridor tracks, connecting to the Northeast Corridor tracks