Complex sentence: In the United States and Canada, some radio stations are granted clear channel status, meaning that they broadcast on frequencies with few other stations allocated, allowing an extended coverage area when skywave propagation takes over at night, starting at or near local sunset.
Split into simpler sentences: In the United States and Canada, some radio stations are granted clear channel status, meaning that few other stations have been granted permission to broadcast on or near their frequency. This allows an extended coverage area when skywave propagation takes over at night, starting at or near local sunset.