The anabaptist religious movements are fascinating. There are Mennonite sects in the US and Canada who live communally and have also lasted a relatively long time.
There's a large Mennonite colony just south of the Amana colonies in eastern Iowa. Apparently, they have little interaction (not that they hate each other, they just don't do business together), but we'd see them both. In Iowa City, we'd see Mennonites in town, actually shopping at Wal-Mart and the like. The Amanas were a much rarer sight unless you actually went to the Amana colonies (which we did regularly, because the restaurants there are some of my favorite places to eat ever).
