Which way do the empties return to Sweet Grass, MT. ?? As mentioned earlier, I never saw eastward empties when I was driving I-40 between Williams, AZ and Albuq.
I imagine they return via the Inside Gateway/Oregon Trunk to Wishram, WA then onto Shelby, MT. Those well versed in the PNW can confirm or correct my assumption.
Well, you most certainly should have seen grain empties on the “Southern Transcon”: Cars released from feed lots in the San Joaquin Valley returning east for yet further loading in the Midwest.
As for the grain trains received from CN and CP, the empties historically return via the Inside Gateway (through Klamath Falls, Oregon). However, many sidings are quite short on this route, so the southward trains run at their optimum length, and the northward trains are restricted to about 4200 feet or so (I forgot the exact length). So, empties go in two sections as far as Wishram, and are combined there.