What is Peekskill?
1.
Located in upper Westchester County, but in downstate New York state.
Anything below the Capital District (Albany, Schenectady, Rensslaer) is downstate. Maybe you should consult a county map of New York State sometime.
2.
Peekskill is
I'm surprised someone from Hartsdale wouldn't agree with me that anything north of Tarrytown is upstate...
See
3.
A city in Upstate New York.
Anything above or on the other side of the Tappan Zee Bridge = Upstate
See