Railroad Archives Online
- CollectionD0063 - Walter W. Ainsworth Collection
- Series004 - Northern Pacific Railroad Company
- Subseries Level 1014 - Photographs
- Subseries Level 2003 - Railroads--Buildings and Structures
- Subseries Level 3003 - Maintenance Facilities
- Subseries Level 3004 - Maintenance of Way support
- Subseries Level 3005 - Signals
- 3 more...