This line definitely has lots of history to it, so intriguing questions.
Backdating the Shasta route to the 1950's would take time, but not impossible (it's nothing I plan on doing, but maybe someone can make a fun private project out of it some day!). It would mean putting back in a number of sidings that were removed, such as Small (below Cantara), Bolam and Cougar up along Mt. Shasta, Erickson, Jerome, Bray, and others north (RR east) of Grass Lake. Dunsmuir's old yard and steam locomotive servicing facilities would need to be restored. And most likely a lot of signals replaced and re-spaced along the route. In the 1950's there were still lower quadrant semaphores on the Black Butte to Klamath Falls segment of the route (which is about 3/4ths of the route), as this portion did not receive CTC until the 60's.
1890's would be vastly more difficult, first and foremost because some 80% of the route did not exist as of the 1890's.At that point, SP's "Natron Cutoff" mainline via Klamath Falls and Pengra/Willamette Pass did not exist, and SP's mainline to Oregon was the Siskiyou Line. So the only portion of my route that would work for the 1890's would be the 20 or so mile segment from Dunsmuir to just south of Black Butte. My above screenshot along the river IS on this segment.
By the way Andre, a pretty spectacular late 1800's route would be Weed Lumber Company's railroad from the mill at Weed up to Grass Lake and beyond, with lots of feeder spurs. It had a roller coaster grade profile as steep as 4% twisting around the base of lava flows on the side of Mt. Shasta. This route was later incorporated into the SP system when they first started building their new mainline via Klamath Falls, and was the last link to get replaced in the 1920's by a much more favorable route between Black Butte and Grass Lake (1.4% max) to complete the new Natron Cutoff mainline. Let me know if you need reference material, if you ever feel the need to dive down yet another rabbit hole.![]()