The Portage Railroad traversed the Allegheny Mountains between Hollidaysburg and Johnstown, Pennsylvania, connecting the Eastern and Western Divisiions of the Pennsylvania Mainline Canal. The mountains represented a formidable obstacle in early transportation routes. The inclines and planes of the Allegheny Portage Railroad provided a unique engineering solution for transporting the canal boats across the mountains.

Allegheny Portage Railroad NHS is located in Blair and Cambria Counties at the junction of the Appalachian Plateaus and Ridge and Valley Provinces in southwestern Pennsylvania. This area is characterized by high, rounded ridges and valleys divided by streams. The park extends linearly from the southeast facing escarpment that forms the eastern edge of the plateau region, known as the Allegheny Front, to the summit of the Cresson Ridge in the Allegheny Mountains.