Railroad Archives Online
- CollectionE0298 - Cordell Newby Photograph Collection
- Series003 - Great Northern Railway Company (U.S.)
- Subseries Level 1014 - Photographs
- Subseries Level 2003 - Railroads--Buildings and Structures
- Subseries Level 3004 - Railroad Tunnels
- ItemCNBk2img208 - South portal of Great Northern Railway tunnel at Seattle, Washington.
- ItemCNBk2img219 - Great Northern Railway Horseshoe Tunnel lower portal in Cascades, Washington
- ItemCNBk2img234 - Great Northern Railway west portal of original Cascade tunnel, Stevens Pass, Washington
- ItemCNBk2img247 - Great Northern Railway Chumstick Tunnel portal in 1965.
- ItemCNBk2img250 - Great Northern Railway Old Cascade Tunnel east portal in 1970.
- ItemCNBk2img251 - Great Northern Railway Pioneer Tunnel, new Cascade Tunnel, west portal, Stevens Pass, Washington