Geographical proximity is another granfalloon.
A granfalloon, in the fictional religion of Bokononism (created by Kurt Vonnegut in his 1963 novel Cat’s Cradle), is defined as a “false karass.” That is, it is a group of people who outwardly choose or claim to have a shared identity or purpose, but whose mutual association is actually meaningless.
http://en.wikipedia.org/wiki/Granfalloon