Ten years after the Macy's Thanksgiving Parade tradition started, the very first Disney character balloon to appear was none other than Mickey Mouse.
Mickey measured over 50 feet tall and was constructed by the Goodyear Rubber Company. Attendants dressed in adult Mickey and Minnie Mouse Halloween costumes guided the gigantic balloon through the streets of New York.
Vintage Disney Memorabilia Blog has the story: Link
Another photo from Flickr user William J. Crawford:
Photo: William J. Crawford [Flickr]