The department store central to "Miracle on 34th Street" is Macy's.
In the original 1947 film, Kris Kringle is hired as the store's Santa Claus after the regular Santa causes trouble during the Macy's Thanksgiving Day Parade. Much of the story unfolds around Macy's Herald Square flagship in Manhattan, linking the fictional courtroom drama and family story to a real New York landmark.
The film was released by 20th Century Fox and became a Christmas classic, winning three Academy Awards. Its parade scenes used footage from the real 1946 Macy's Thanksgiving Day Parade, giving the movie an unusually documentary-like connection to the holiday tradition.
A common mix-up comes from the 1994 remake, which changed the store's name to the fictional "Cole's" because Macy's did not permit its name to be used. That change applies to the remake, not the original film or the standard trivia answer. The 1947 movie's department store is definitively Macy's.