sideFrom the Wikipedia article on range safety:
Rockets are usually launched into a space above the launch range called the launch corridor. If rocket engines fail while the rocket flies inside the corridor, the rocket falls in an uninhabited area. Engine failure outside the launch corridor may cause the rocket to fall on people or property. Therefore, if the rocket is about to exit the launch corridor, the RSO will terminate powered flight to ensure that no debris falls outside the launch corridor.
The launch corridor or hazard zone is usually a corridor in the direction of launch. What will be the shape of hazard zone for a rocket flying back?
Flight Corridor for Guided Suborbital Vehicle
Keep Out Areas SpaceX requests for each launch. Eventually, the red zone will cover one of the most dense populated areas in US if Falcon 9 try landing on 'Landing Site 1'.