Again, how does one separate NYC CSA from Philadelphia CSA?
It's a legitimate question. If there is factual data and documented trends, as you state, to prove that it can be done without being arbitrary, then I'm seriously interested in understanding how.
For example, why is Trenton officially part of NYC when geographically and functionally it is much more closely associated with Philly? And considering that Bucks County displays major commuting patterns into the NYC metro area, why is it solely part of Philly? Is the Delaware River the dividing line? If so, why is Allentown part of NYC?
It's all BS. The answer is, you cannot separate the two via non-arbitrary means. Where do you split Jersey?