I have long been amused at the FCC obsession for 1560 in NYC having to protect the co-channel in Bakersfield, which is 2,450 miles away (for the moment I will ignore any nearby first adjacents.)
Tune through any of the AM frequencies at night, and every last one of them is a pileup of multiple co-channel stations clobbering each other. And these are stations that are much closer to each other than Bakersfield is to NYC. In short, the AM band is a complete, incoherent, cluttered mess, and has been that way for the past 40 years.
If the NYC 1560 was to run 50kw non-directional, I doubt that anyone west of the Mississippi River would notice or care.
Keeping to the rules of the NARBA treaty, which is from 81 years ago is stupid. The days of "clear channels" and regional channels useful (and needed) over a large part of the country are long gone. Nobody, outside of the hard-core AMDX community, listens to distant AM stations.
It is long past time to scrap NARBA, let stations ramp up the nighttime power and antenna parameters, and let them adequately cover their home markets with a solid signal. Anything beyond the home market is irrelevant.
It's not the 1930s any more. Or has the FCC not noticed that?