This stationery uses the post-1936 Rocky logo, but is probably from before the war. The carelessness of the printing–the off-center red circle and the slight tilt of the lines of text relative to the edge of the paper–suggests this was used aboard a secondary train, as such imperfections would not have been acceptable on a first-class train such as the Empire Builder (not to mention that Empire Builder stationery would probably show the name of the train).
Between 1937 and 1947, the only trains in Great Northern timetables listed as having parlor cars were the St. Paul-Duluth Gopher and Badger and the Portland-Seattle trains. Cafe cars were in trains 3 & 4, the Seattle-Spokane Cascadian, the St. Paul-Fargo Alexandrian, St. Paul-Grand Forks, Havre-Butte, Williston-Havre, and Seattle-Vancouver. This stationery could have been used on any of those trains.