There's a strange link between 1939's The Wizard of Oz and Fallout
If you think about it, Diamond City and the Emerald City are the
same. Not only because of the colour coincidence but because of the references. We see Dorothy at the beginning of the trail, with a
swirl of red and yellow brick. In Fallout 4, if you follow the
Freedom Trail left by the Railroad, you follow the red brick road,
whereas in Oz, Dorothy only follows the yellow. It's almost as if the
red trail takes you in the opposite direction to Diamond City...