Right so this has been nagging at me for a while and I'm glad someone else brought it up.
Looking back through the reports I've been cataloguing since about 2019, there's a genuine cluster pattern forming around disused rail corridors. Not just America either - we've got similar anomalies appearing near old industrial lines here in the UK, though obviously the Dogman label gets slapped on things differently over here.
My working theory is that it's got nothing to do with the rails themselves and everything to do with what grows alongside them. Abandoned rail lines become these long uninterrupted wildlife corridors - dense undergrowth, minimal human traffic, natural tunnelling through landscapes for miles. If something large and cryptid-adjacent wanted to move between territories without being seen, that's basically a motorway for it.
The other angle nobody wants to touch is the electromagnetic one. Old iron tracks, some still carrying residual charge, running through areas with unusual geological features. Remote viewing sessions I did last year picked up something interesting near a particular derelict line in the Peak District but thats a whole other thread.
What specific lines are people seeing these clusters around?