I know a lot of mainstream families, strangely enough, in the NE who didn't have huge numbers of children, but did teach them a la Gothard in the 70's and 80's. There are pockets of 'followers' all over the place, in all kinds of denoms, in all kinds of cultural and social climates, all over the US.
It's very UScentric, because they are all about how we will need to be self sufficient once our country 'falls' due to all the sin and the way we've allowed homosexuals and women so much control, like the evil, debauched Europeans....