Why was Lucy uncomfortable during the trip she took with William to Bangor, Maine in the novel, Oh, William!?

During their trip, Lucy feels overwhelmed by an old and familiar sensation. The desolate landscape, the dilapidated houses, and the absence of people remind her of her childhood. She feels unnerved and disoriented. Eventually, however, she realizes that this parallel between Maine and Illinois might teach her something about her origins and herself.