Railroad Archives Online
- CollectionD0011 - James M. Fredrickson Collection
- Series004 - Northern Pacific Railroad Company
- Subseries Level 1014 - Photographs
- Subseries Level 2004 - Railroad Tracks
- Subseries Level 3002 - Railroad crossings
- ItemJMF04-02990.0 - Northern Pacific grade crossing at McKenna, Washington, circa 1927.
- ItemJMF04-03008.0 - Northern Pacific facilities at DuPont, Washington, circa 1927.