What does the "river" in "The Farming of Bones" signify?

The Massacre River, named for a mass slaughter in the seventeenth century, lives up to its name in the events of the book. Throughout the book, the river is a place of actual and symbolic death: many people die in it, corpses float down it, and once people cross it, their lives are never the same. Crossing it a second time is even harder, leading to alienation: you can never truly go back to the other side.