Right so I went down a proper rabbit hole on this last night and the railroad correlation is actually mental when you look at the data. Old rail lines follow natural corridors through forests and valleys, which means they basically act like wildlife highways, and if Dogman is a real flesh and blood cryptid rather than some interdimensional weirdness then it makes total sense it'd use the same routes.
Also worth noting that a lot of old rail lines in the US (and honestly here in the UK too if you count old trackbeds) cut through land that was previously considered boundary territory by indigenous communities. Liminal spaces and all that.
Could just be confirmation bias though, like people are out near railroad lines more and therefore reporting more. Someone needs to actually map teh sightings properly instead of just vibes. Has anyone tried overlaying the reports with old rail maps? Because if theres a genuine spatial correlation that would be genuinely interesting rather than just spooky anecdote territory.