Pete Warden has been visualizing Facebook connections, and has noticed that some local networks form clusters in surprising ways.

[I]t’s been remarkable to see how groups of them form clusters, with strong connections locally but few contacts outside the cluster. For example Columbus, OH and Charleston, WV are nearby as the crow flies, but share few connections, with Columbus clearly part of the North, and Charleston tied to the South[.]

Some of these clusters are intuitive, like the old south, but there’s some surprises too, like Missouri, Louisiana and Arkansas having closer ties to Texas than Georgia. To make sense of the patterns I’m seeing, I’ve marked and labeled the clusters, and added some notes about the properties they have in common.

With the above map as the result. Via Kottke.