Well all the Bosses of each Family will know the bosses of each other Family, at least by name. Think of Apalachin in the late 50's when bosses from all over the States came for that one disaterous Commission meeting.

Mick, on a smaller scale, think of Gateshead/Newcastle. You'll probably know a few names of the nutters, hard baskets around there. The one's you don't know will be nobodies. They've all heard of each over.

Donnie Brasco goes into well with a move to Milwakee. He managed to get in with some mob guys there because they knew who Lefty was from Mulberry Street. Up until then the Milwakee guys nearly whacked him because they thought he was a nobody.