The great part of the migration was from 1895 to 1914. I have often wondered about the ones my grandparents left behind, with half a town emptying out. Some of the ships manifests asking for closest relative they were leaving listed in-laws. Some of the later travellers listed "none" under relatives in Italy.
IThere is a cookbook "The Men of the Pacific Street Social Club" (available from any library in the United States) that says our area in Brooklyn was entirely populated by people from Pomigliana d'Arco. I do know my mother walked from Acerra through Pomigliana as a very little girl so the distance could not have been very great. One side of her family was from Acerra and the other parent was from Sant' Anastasia across Pomigliana and up the mountain.
There are several places where these people of whatever name went: Chicago Illinois, Sharon and Wilkes-Barre Pennsylvania , all of New Jersey and Brooklyn New York, Rochester in Upstate New York, all of Connecticut and the Berkshire Mountains of Massachusetts. The reason the cousins all came and stayed together is that they had connections for housing and jobs.
Many of my people also went to Buenos Aires in Argntina and Sao Paulo in Brazil. These countries were considered as promising as the United States in those years. In fact, I believe that the largest group of Italians outside of Italy is in Brazil, and Argentina is 60% Italian.
I'm afraid I really don't know any more information than what I listed in my first posting. There are four tapes that the Mormon Church has on Acerra and the surrounding area for marriage records. Your cousin in Italy might start there on www.familysearch.org
to look for familiar names. As an example, one name of my family line, Cerulli, has died out or been lost through marriage as far as I know. But I believe they were the link through which all my great great grandparents were related. So you have to be inventive in your searches!
Please keep in touch.