This has been sitting in the back of my mind for a couple of years now. Looking at the sighting maps from the BFRO and a few independent researchers, there does seem to be a genuine clustering along old rail corridors, particularly in the American Midwest but also cropping up in some Scottish accounts closer to home.
My working theory is that it's not coincidental. Old rail lines follow natural geographic contours - low ground, river valleys, passes through high terrain. These are the same corridors wildlife has used for centuries. If something like a Dogman exists and is territorial or migratory, it would logically exploit those same routes.
There's also the electromagnetic angle worth considering. Old iron rail lines can act as conductors and some researchers have linked electromagnetic anomalies to paranormal entity behaviour more broadly. I don't think that's the primary explanation here but it shouldn't be dismissed outright.
Has anyone done actual GIS mapping of sighting coordinates against historical rail line data? That kind of spatial analysis would either confirm the pattern or kill it quickly. Would love to see someone run the numbers properly.