In the same county (Washington County) but no, not here in St. George. The FLDS is on the Utah/AZ border, but still in this county. We DO see them in the big box stores here, however. They are quite the sight. Usually, when they hop out of the van, someone will holler the pejorative term to them “Polygs!” (pronounced “pligs”) It is the equivalent of hollering the N-word at a van of black folks...quite insulting.
There is a more modern polygamy thing going south of here (but in AZ) known as Centennial Park.
I took a back road up from Vegas to Mead to St George....four years ago
And looped around northern AZ from Vegas to Grand Canyon and back up to I-15
MIGHT HAVE BEEN ONE OF THOSE TOWNS