Railroad Archives Online
- CollectionD0027 - Timothy Miller Collection
- Series003 - Great Northern Railway Company (U.S.)
- Subseries Level 1009 - Engineering Records
- Subseries Level 2008 - Physical plant drawing
- Subseries Level 3008 - Tunnels
- ItemStruc000877 - Great Northern Engineering Drawing, Cascade Tunnel, Washington, 1955
- ItemStruc000878 - Great Northern Engineering Drawing, Cascade Tunnel, Washington, 1955
- ItemStruc000879 - Great Northern Engineering Drawing, Cascade Tunnel, Washington, undated
- ItemStruc000880 - Great Northern Engineering Drawing, Cascade Tunnel, Washington, undated
- ItemStruc000881 - Great Northern Engineering Drawing, Cascade Tunnel, Washington, 1955
- ItemStruc000882 - Great Northern Engineering Drawing, Cascade Tunnel, Washington, undated
- ItemStruc001245 - Great Northern Engineering Drawing, Flathead Tunnel at Twin Meadows, Montana, 1973
- 345 more...