Doesn't sound quite the same - but up near my country place there's a significant population of Apostolic Lutherans. They generally keep to themselves, and live a fairly modest / old-fashioned existence. Not quite the Amish - they own cars and use electricity and such, but not television, etc. They're a fairly small group but stick together.
I imagine that there's a lot of splinter groups like that and so identifying the particular one may not be easy.
I imagine that there's a lot of splinter groups like that and so identifying the particular one may not be easy.