New York

The New York Megapolitan Area should also be split up for comparison purposes. I now show it as 1.28 tn gdp. (Source). Here are the parts:

1. New York City and Long Island.  NYC itself has 8.2 million.  Nassau County has 1.3 million, and Suffolk County has 1.5 million, Westchester County has 949,000, and Rockland County has 312,000 for a total of 12.3 million.  For census purposes, this is the New York-White Plains-Wayne, NY-NJ Division + the Nassau-Suffolk Division - 3 counties in NJ (Bergen, Hudson, Passaic).  The gross NY state product is $1.16 trillion, and the population of the whole state is 19.5 million.  The estimated GDP of NYC itself (the areas listed above) is $850 bn.
2. Northern New Jersey. Bergen, Essex, Hudson, Mercer, Middlesex, Monmouth, Morris, Passaic, Somerset and Union counties.  Total population 6 million.  This is the Edison-New Brunswick, NJ area + Newark-Union, NJ area plus the three counties above less a couple of small counties.  The gross NJ state product is $497 bn and the population is 8.8 million.  So a reasonable estimate would be $339 bn.
3. The Connecticut parts are in the Bridgeport-Stamford-Norwalk MSA.  This has 889,000 residents and a GDP of $85 billion.