Many people think that A Nightmare on Elm Street 2 happens in 1986, one year before the 3rd movie. But I have source to counter it. In the 2nd movie, Jesse finds Nancy's diary, which states that it was written 5 years before the 2nd movie. In the first movie, Nancy is 17, while in the 3rd movie, she is 21. Since he found her diary 5 years after, then Nancy must have been 22, not 21, meaning that the 3rd movie takes place in 1986, while the second one takes place in 1987.