I imagine that this is the Snake River for I can not conjure any alternative, and yet with a Google Earth skimming of its winding way between Hell’s Canyon and the Columbia River I did not quickly find any part of that river that has these curves with a railroad track running beside the far shore.   But then I only I only traveled from east to west  assuming that the scene is exposed from a sun that is off to the left and so  more likely in the west on an afternoon in the late 1940s, which is before any of the three dams were along the last part of the river.   With time – tomorrow perhaps – I will return and try again heading then from the west.  (Click TWICE to enlarge.)