Road systems in the DeCandido novels

DeCandido relied heavily on accurate US road maps when writing Extinction to describe a realistic route for the characters to drive through, and what towns they would have come across between scenes. The attention to detail is made very clear in Chapter Four, where DeCandido gives a brief introduction to the modern American road systems, and describes how odd and even-numbered Interstates conform to a north/south and east/west direction, respectively.