OddRails, To be honest I found these by firing up Google maps after reading the book "Guide to the Milwaukee Road in Montana" by Steve MCarter. It's a great little book with a brief history of the Milwaukee Road in Montana followed by a guidebook to what still remains and can be seen. It contains lots of historical photos, although many are not that clear. Unfortunately, it was written in 1992, and some of the things he sites as still viewable are gone by now. Ingomar had a boxcar, but I could not find one. There are other box cars named, but I found none of them. Primrose substation still had a couple of bungalows, but these seem to be gone. And he even mentions things that were disappearing as he wrote. But I am with you Rob, I would love to spend a summer exploring all the way from the eastern border of Montana to Rattlesnake Lake, Washington, west of the summit of the Cascades, which is as far west as I believe you can follow the ROW.
Here is one more link (no street view). It shows where we lived when I was born. My father worked the Doris, Washington substation, which supplied power to pull the train up west from the Columbia Gorge to the Ryegrass summit on the way to Kittitas and Ellensburg. Now just three house foundations and the concrete pad for the substation. And the old sheep pens just a little to the south where my brother used to wander off. We lived in the house at the far end. My brother and I plan to hike up there some day and look around. Not much to see, but lots of stories I can tell. And why I keep hoping Tume will update and release his Othello to Kittitas stretch someday!
https://www.google.com/maps/place/D...73626e9!8m2!3d46.8676312!4d-120.0097746?hl=en
EDIT: Well, it looks like the ROW can be tracked as far as Maple Valley, Washington, but I am not sure about access beyond Rattlesnake Lake. We lived at the lake (Cedar Falls) after being at Doris. All of that is gone but a plaque, I think, but I need to get up there and look. Fortunately Washington bought the ROW and it is now the Iron Horse Trail, and Palouse to Cascades State Park.