Railroad Archives Online
- CollectionD0063 - Walter W. Ainsworth Collection
- Series004 - Northern Pacific Railroad Company
- Subseries Level 1014 - Photographs
- Subseries Level 2004 - Railroad tracks
- Subseries Level 3001 - Railroad mainline
- ItemWWANT112 - Northern Pacific mountain right-of-way from Stampede, Washington, circa 1925.
- ItemWWANT115 - Northern Pacific mountain right-of-way at Borup, Washington, circa 1925.
- ItemWWANT116 - Northern Pacific mountain right-of-way at Borup, Washington, circa 1925.
- ItemWWANT117 - A Northern Pacific steam locomotive at Stampede, Washington, circa 1925.