Slatington · US

Lehigh Tunnel South Portal

The Lehigh Tunnel South Portal is where the Pennsylvania Turnpike's Northeast Extension (Interstate 476) slips beneath Blue Mountain on its way between the Lehigh Valley and the Poconos. Far from a quiet heritage stop, it is a working piece of heavy transportation infrastructure—the entrance to the southbound tube that carries two lanes of traffic toward Philadelphia—and it rewards exactly the kind of attention road travellers and engineering fans give it: the bold lettering over the portal, the smooth oval concrete of the newer tube, and the sense of a highway disappearing into the side of a mountain. Its appeal lies less in what you can wander around than in what it represents: the only road tunnel on the eastern Pennsylvania Turnpike, a twin set of tubes that record four decades of changing tunnelling methods, and the sole highway tunnel in the United States that the Appalachian Trail crosses overhead.