When the local 5kw daytime station on 1030 signs of for the evening, WBZ really booms into my Michigan QTH.
Most evenings WBZ can even be heard on my xtal set as loud as any local station.
The reason for the powerful signal may be the fact that WBZ uses a two tower array to
produce a directional signal beaming its 50kw westward. None of its signal is wasted heating up the
Atlantic ocean. Also, the transmitter site being in what appears to be a salt marsh probably
helps provide an excellent ground for the towers.
AFAIK, the only other Class I-A clear with a directional pattern is WWL AM 870 New Orleans.