Railroad Archives Online
- CollectionD0011 - James M. Fredrickson Collection
- Series004 - Northern Pacific Railroad Company
- Subseries Level 1014 - Photographs
- Subseries Level 2003 - Railroad Buildings and Structures
- Subseries Level 3001 - Bridges
- 73 more...
- ItemJMF04-03132.1 - Northern Pacific swing bridge at Hoquiam, Washington, in September 01, 1924.
- ItemJMF04-03132.2 - Northern Pacific swing bridge at Markham, Washington, in September 01, 1924.
- ItemJMF04-03146.1 - Northern Pacific truss bridge at Chehalis Junction, Washington, in September 11, 1924.
- ItemJMF04-03148.1 - Northern Pacific truss bridge at Millburn, Washington, in September 11, 1924.
- ItemJMF04-03165.1 - Northern Pacific truss bridge at Lebam, Washington, in September 11, 1924.
- ItemJMF04-03165.3 - Northern Pacific truss bridge at Menlo, Washington, in September 11, 1924.