North of the city, the counties within the CMSA ... are Westchester, Rockland, Orange, Putnam and Dutchess.
That's true today, but wasn't when I was growing up there in the '50s and '60s.
The Census Bureau seems to have a policy of expanding CMSA's, to encompass areas once considered beyond the core city's sphere of influence. It's probably not a bad idea, all things considered, as it reflects economic and demographic reality to some extent. Increased housing prices and the dispersal of jobs into suburban and exurban areas are the main factors. For instance, Dutchess County is said to be attracting new residents on account of its housing prices, which are more reasonable than those in closer suburbs. While commuting times from much of the county to the city are long, they're not so bad for people working, for example, in Westchester. Parts of the Poconos have attracted New Yorkers for the same reasons. These areas may seem remote with respect to the city, but they aren't necessarily so remote for people working in New Jersey. These trends occur in other parts of the country as well.
Of course, the northern New York counties in question - Rockland, Orange, Putnam and Dutchess - all have commuter rail service to the city (or at least Hoboken).