In the movie miracle on 34th street the final proof that Kris kringle was actually santa Claus was provide by?

Answer 1

The United States Postal System was willing to deliver the mail addressed to "Santa " to Kris Kringle at the local court house. So it was a department of the federal government that made the determination. But it was never actually "proved" that he was Santa.

Answer 2

if memory serves me right its because the postal service sent him all mail addressed to "santa clause," and because supposedly the postal service never sends mail to the wrong person, that would mean he is santa clause.