In Back to the Future Part II, Marty and Dr. Emmett Brown go to which future date?

In "Back to the Future Part II," Marty and Dr. Emmett Brown go to the future date of October 21, 2015. This date was chosen because it was approximately 30 years into the future from the original release of the movie, which was in 1985. By setting the story in the near future, filmmakers were able to envision and depict what they thought technology and society might look like, resulting in a futuristic setting for Marty and the Doc's adventures.