Information about the time and the country "The chosen one"

My book plays around the Ironton County. There are six cities in America that are called Ironton but I couldn't find the right one because most things happen in a compound which is in a desert 50 miles away from Ironton (There is the compound the book mainly plays at).
I think my book plays at the end of the 20th century because a girl used a cell phone but all the locations in the book don't seem that modern to me and I think polygamy (more information in the summary) was more common in the past.