Question

The Federalist was written to

Answer 1

win support for the Constitution in New York.

Answer 2

In general the Federalist papers were written to get public support for the constitution in all of the states- however, they were especially written for New York. Wikipedia says "Hamilton began the Federalist Papers project as a response to the opponents of ratification, a response that would explain the new Constitution to the residents of New York and persuade them to ratify it."

So I guess your answer is New York