Why does the author go into depth regarding the geography of her hometown in Chapter 5?

Bechdel draws maps and describes the geography of Beech Creek as a way of relating the isolation of her hometown. She describes the Appalachian ridges that surround Beech Creek and the Allegheny Plateau, saying that "Perhaps the peculiar topography really did exert some kind of pull" as a way of explaining why her father would have chosen to live in such a rural and closed-minded setting.