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
- 347 more...