I was just in your area in October and they seemed to be rebuilding the BNSF tracks that run southwest out of Klamath. When I was through there about a decade before, those tracks seemed to be seldom used. Tule Lake National Wildlife Refuge BNSF (0991)

I've followed that track on Google Earth quite far into CA (because I do that sort of thing - ha!), but don't know anything about the rebuilding. I grew up here and moved back five years ago. The amount of BNSF and Southern Pacific traffic is surprising to me, since the lumber industry is barely producing anything in the Klamath Basin. Maybe they're mostly passing through. You really get around, Don!

There seems to be an increase in rail traffic in general, much of it just passing through. There's a lot of raw materials (e.g., minerals) from the inland portions of the country moving to the ports and then finished products coming from overseas and going inland. There's a fairly limited set of tracks crossing the mountains of the west, so this may be a main route for traffic from Portland/Seattle to the mid-section of the country.

Interesting, I hadn't thought about the mountain range issue. I do think the rail that goes from here to eastern CA ends up in Reno and I suppose points east. I like to follow tracks, but when I'm on Google Earth I stop to look at other things, so can't seem to get far! I have GE-ADHD!

Aha! I just happened across this: www.oregonlive.com/environment/index.ssf/2014/10/oil_train_traffic_increases_th.html
That explains the huge numbers of black tanker cars I see.

GE-ADHD (Google Earth attention deficit hyperactivity disorder)? I like that acronym, mind if I use it? I've never understood why people are using GPS systems in their cars, mainly because it limits the ability to see all the interesting side trips one might take! I guess some people just can't handle their own curiosity!

The rail line goes down to Oroville and then Sacramento, but I think most of the traffic you're seeing through there probable branches east from Oroville through the Feather River canyon, which then takes it north across Nevada through Gerlach and on to Winnemucca. Here's just one shot I've got from that line: