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 3003 - Maintenance Facilities
- 843 more...
- ItemStruc006980 - Northern Pacific Engineering Drawing, at Helena, Montana, undated
- ItemStruc006986 - Northern Pacific Engineering Drawing, at Helena, Montana, 1968
- ItemStruc007010 - Northern Pacific Engineering Drawing, Roundhouse at Helena, Montana, 1963
- ItemStruc007012 - Northern Pacific Engineering Drawing, Unnamed Structure at Helena, Montana, 1963
- ItemStruc007013 - Northern Pacific Engineering Drawing, Roundhouse at Helena, Montana, 1960
- ItemStruc007014 - Northern Pacific Engineering Drawing, Roundhouse at Helena, Montana, 1961
- ItemStruc007015 - Northern Pacific Engineering Drawing, Roundhouse at Helena, Montana, 1960
- ItemStruc007016 - Northern Pacific Engineering Drawing, Roundhouse at Helena, Montana, 1960
- ItemStruc007017 - Northern Pacific Engineering Drawing, Roundhouse at Helena, Montana, 1960
- 459 more...