I bring up this discussion in light of this fascinating visualization, "Mapping Generic Terms for Streams in the Contiguous United States". The discussion of the map can be found here:
There are a few patterns on the map that I haven’t been able to figure out. West Virginia shows a sharp north to south division between runs and branches that continues to puzzle me. Some other geographic patterns I’ve noticed in WV largely run parallel to the Appalachians, from the SE to NW. I don’t know much about the area, though, and I have no idea what could be behind such a distinct division. Any West Virginia-ites willing to take a stab? I’m also intrigued by the patch of branches in southwestern Wisconsin, which I suspect may have something to do with the diffusion of naming practice by way of branch-loving Appalachian miners during a regional lead mining boom in the early 19th century.
I encourage you to read the comments section to find some possible solutions to the posed puzzle. The cartographer references a map of NFL allegiances that's a pretty good approximation of the "branch-loving" part of the country. What I see is Pittsburgh migration and thus the metro's economic region. There is a historical precedence for all the talent churn between Pittsburgh and Washington, DC.