I've seen this picture before and am trying to figure out where it could be. The tracks cross the Meramec at Moselle but never run parallel to the river there as far as I can tell. Probably closer to Robertsville?
Yes, this a real location ~ 1.5 miles SW of Robertville and ~ 3 miles NE of Moselle. Frisco had about 3 postcards with similar pictures for this site. Hard to find anywhere else riverside this nice. They likely used the name Moselle because it had a larger station and years prior was a home to the nearby blast furnace where the Frisco severed.