Do TV the old analog TV signals have anything to do with radio market? The reason I ask is that, before cable TV, eastern Long Islanders relied on Connecticut stations for TV.Markets are defined by Nielsen (and previously by Arbitron) based on a combination of what "core market" stations are listened to and, secondarily, the commute patterns.
Most markets were defined well before FM became a major factor. And a revision that affects other markets requires subscribed stations in both markets to be consulted. In the case of Sussex, it is not part of another market but back when the NYC Metro Survey Area was defined, most AM stations did not have a good signal there because those located in the Meadowlands were directional away from NW New Jersey. And when the market was first defined, FM had very little listening anywhere.
If you look at the "usable" 60 dB/u signal of ESB FMs, it does not cover that country. And few of the AMs have a 10 mV(m signal out there, even in the easternmost part of the county.
I no longer live on Long Island, so I'm not familiar with OTA TV viewing as you head out east on The Island.