Railroad Archives Online
- CollectionD0027 - Timothy Miller Collection
- Series004 - Northern Pacific Railroad Company
- Subseries Level 1009 - Engineering Records
- Subseries Level 2008 - Physical plant drawing
- Subseries Level 3001 - Bridges
- 6765 more...
- ItemBB028732 - Northern Pacific Engineering Drawing: Detail of Bent 4, Bridge 51 (50), West of Spire Rock, Montana, undated
- ItemBB028733 - Northern Pacific Engineering Drawing: Detail of Bent 6, Bridge 51 (50), West of Spire Rock, Montana, undated
- ItemBB028734 - Northern Pacific Engineering Drawing: Detail of Bent 7, Bridge 51 (50), West of Spire Rock, Montana, undated
- ItemBB028735 - Northern Pacific Engineering Drawing: Detail of Bent 8, Bridge 51 (50), West of Spire Rock, Montana, undated
- ItemBB028736 - Northern Pacific Engineering Drawing: Detail of Bents 9, Bridge 51 (50), West of Spire Rock, Montana, undated
- ItemBB028737 - Northern Pacific Engineering Drawing: Detail of Bents 11, Bridge 51 (50), West of Spire Rock, Montana, undated
- ItemBB028738 - Northern Pacific Engineering Drawing: Detail of Longitudinal Brace, Bridge 51 (50), West of Spire Rock, Montana, undated
- ItemBB028739 - Northern Pacific Engineering Drawing: Detail of Longitudinal Brace, Bridge 51 (50), West of Spire Rock, Montana, undated
- ItemBB028740 - Northern Pacific Engineering Drawing: Detail of Plate Girder, Bridge 51 (50), West of Spire Rock, Montana, undated
- 954 more...