The Bronx was once part of Westchester.
Nassau was once part of Queens.
Rockland was once part of Orange Co.
Ergo, Rockland is upstate.
"I live in Coney Island, and that Rockland place 50 miles north of me is definitely *NOT* upstate, but that Orange County place which is 60 miles north of me definitely is!" -the way Rocklanders want New York City residents to think
In the Bronx, anything north of Yonkers is upstate. (OK maybe Hartsdale, but thats it)