Railroad enthusiasts for that area. They'll focus on the trains, not who rode them, but they'll probably want to highlight how the trains benefited the area's communities. So look for local train clubs, etc., and quite often the model railroaders and the real-train folks will be the same folks.

A friend of ours has written extensively (and included archived photos donated by other enthusiasts) on train history, and when I run into him I'll see if he knows about any orphan train experts.

I think that what people are trying to point out here is that if a train went through your county, chances are good that one day at least, when the regularly-scheduled, familiar train pulled in, it might have had a lot of ticket-holders who were kids with cards hanging down their shorts, and people seeing this would have said, "Oh! This is one of those Orphan Trains I've heard about." Just think of a usually-partially-empty train, running on its regular schedule, happening one day to be carrying a load of kids. The train is the train-- it's transportation.

~S~