Keystone is a state first mentioned in the episode "Press Start to Begin". Its nickname is "The Great State" and is adjacent to Delmarva, the location of Beach City.
History[]
Season 5[]
Pearl, Star Quartz, Peridot, and Emerald go into Keystone when the Keystone Shredding Contest was about to start. Sabina was heading to the same contest herself, and where she first met Pearl.