Speaking of coal strings, several years ago, Mrs.D and I took a road trip up to the Black Hills area, on back roads (some gravel) from KC, up through the Nebraska Sand Hills, into SD. As we traveled west (I don't remember the highway) we were travelling along a double road (two track sets, one for trains in each direction), which carried nothing but coal strings......one after another, spaced perhaps fifteen to twenty minutes apart, fully loaded going east, and equally spaced empties deadheading west. We assumed they were coming from the coal fields in western Wyoming and Montana. It was a massive display of RR hauling capability.
Don't know where they are divided and routed to their ultimate destinations, but some of them come through here, on the N&S road about a mile from our house. We also see coal strings bound for local power plants coming from the Peabody fields in SW Missouri and SE Kansas.
You went up Nebraska Highway 2 towards Chadron, which would be the only possible scenario with the picture you painted. That was the old Chicago, Burlington & Quincy line, now I guess the Burlington Northern unless they changed their name again.
You went right through the town where I spent my adolescence.
This was the Hastings (near Grand Island)-Billings, Montana, branch line of the old CB&Q. When I was growing up, it was a little-used line. The "division points" were at Grand Island, Ravenna, and Alliance. Alliance, on the outer western edge of the Sandhills, was the major point.
During the Reagan-Bush-Gingrich-Bush prosperity, this once little-used line was double-tracked to bring coal from Montana further south, and it's been a very lucrative business for the Burlington Northern (if it's still called that). For a while, I guess, a few years back, it was also the longest line using strictly continuously-welded rails.
It's much different than it was when I grew up there, again the result of tax-and-spend policies that encouraged opening up the remote areas.