Most of the original "clear channel" stations are nondirectional 24 hours. Some stations, such as WBZ, could operate as nondirectional, but instead use a directional pattern to avoid sending large amounts of signal into the ocean. The formats and call letters on this list are probably not 100% up-to-date, so send any updates to email@example.com.
*CBW drops to 46kW at night. Close enough!