In Season 4, there are the light beacons that surround Promise City. .
The beacons delineate the territory between normal Seattle and Promise City, but I couldn't figure out what they were exactly. Were they simply passive notification systems like signboards, or were they actually the devices that kept people out? If they were keeping people out, how ere they created and controlled? And how exactly do people pass over the border, can any P-positive just step over?
