(Ulster, Columbia and Rensselaer counties as "downstate" also since they pay MTA taxes).
Correction: MTA taxes stop at Orange and Dutchess. These can be considered either Downstate (some commuters in some areas) or Upstate (mostly rural).
After the last census, both Orange and Dutchess were part of the New York CMSA. Like all CMSAs, New York was divided into component PMSAs. One included Nassau and Suffolk. Another included New York City, Westchester, Rockland and Putnam. Dutchess and Orange were each separate PMSAs in the NY CMSA. They were after 1970 and 1980 as well.
Everything else is considered "Upstate" by everyone except the Regional Plan Association, which includes Ulster, Sullivan, and Hartford! counties in the NY Metro Area. And the BEA "economic areas," which place much of Vermont, all of Connecticut, and a good chunk of Pennslyvania in New York's orbit.
BTW, MTA taxes for Columbia are a big issue. People there want MTA service for second homeowners, but are unwilling to pay the tax. They are demanding something for nothing, and hoping NYC can be made to pay. The MTA wants to extend the Hudson line to Rhinecliff, but Rhinebeck residents don't want it, because it might attract the lesser people. The City of Hudson wants it, but is outside the MTA area. Etc, etc.