Railroad Archives Online
- CollectionD0237A - Great Northern Railway Historical Society Cascade Division Collection
- Series003 - Great Northern Railway Company (U.S.)
- Subseries Level 1014 - Photographs
- Subseries Level 2003 - Railroads--Buildings and Structures
- Subseries Level 3007 - Tunnels
- ItemGNRHSCD035 - Seattle Tunnel, Seattle, Washington, 1969