Anywhere i go in America, and even outside the U.S., everyone can usually tell that I am from NYC/NJ area. I have, at least to the rest of the country, a distinct Brooklyn/Italian, NYC accent. Its a "localized" Staten Island/Brooklyn accent.
In fact, when i am in New Jersey, which is where i live now, New Jersey people can actually tell that i am from Staten Island NY. I sound different, and specific, to them, but to people from other parts of the country, I just sound like an Italian American from NYC.
Where i am from, Staten Island/Brooklyn, there is really no other group that sounds like us. We are distinct, NY accent, all by itself. It is, probably, do to an isolated population being "trapped" on a single "island", and one specific national group, Italian American.
In fact, even the Italians that came to NY, directly from Italy, and still speak mostly Italian, have their own Italian dialect. It is not spoken ANYWHERE else in the world, except Brooklyn/Staten Island. It is a mix of mostly Italian words, mixed with English "slang" words, and expressions, unique to NYC. One of my ex-girlfriends father spoke it. Italians coming directly from Italy, could NOT speak this form of Italian/English. It is just spoken by Italian speaking, "old timers", who have been in America/NYC, for years, but never fully learned English.
Now, back to my NYC/staten Island accent. To most New Yorkers, i actually have a very "mild" accent, but to the rest of the world, they know i am from NY when i speak.