Primary Sources
Images:
- Portage railway
- 1855 map of Altoona and the mountain ridges crossed by the railroad.
- Map of Pennsylvania Railroad system in the 1870s
- Panoramic view of the Pennsylvania Railroad shops in Altoona.
- Interior view of one of the PRR shops
- Railroad trestles helped raise the valleys.
- The Horseshoe Curve, Altoona, PA