I've always been fascinated with the Northeastern states. Look at how tiny they are! It takes me four hours to get to the next state from California; you can get through several states in that time on the East Coast. You can also get from Boston to New York in a little less time.
Which makes the geography of Yankees and Red Sox fans quite interesting. There are all these wee states with no baseball teams, yet they're bound by the gravity of metropolitan areas to pick one of the big two teams. Which areas pick what?
Ben Blatt, way back in 2012, did his best to figure out the geography of the rivalry. Hey, it's new to me. His conclusion: There are a lot of deeply confused states.
You can see that many towns had more than 50% of one fanbase but were put in the other’s territory. While you could play around with the borders more, there are many places where it would be impossible to draw a contiguous border and not have any outliers like this.
Next step: An overlay of police reports pertaining to bar fights.