In what year did John Grisham's story, A Time to Kill, take place? In what year did Harper Lee's To Kill a Mockingbird take place? 1955?

John Grisham, in A Time to Kill, does specify the year in which his story takes place.  The closest he comes in his description of Omar Noose, the judge who will preside over the trial that provides the basis of Grisham’s novel about racism in the American South.  In that description, the author provides the following comment regarding Judge Noose: “That's how ex-State Senator Noose became Circuit Judge Noose. He was elected in 1975, and reelected in 1979 and 1983.”

So, we now know that Judge Noose was most recently reelected in 1983.  Circuit judges in the State of Mississippi serve four-year terms, as noted in the above quote, which is consistent with the state’s website for its Judicial Branch [See: https://courts.ms.gov/aboutcourts/aboutcourts.html].  Consequently, the year in which Grisham’s story takes place would be (assuming the election occurred in November of 1983, with the judge being sworn into office the following January) between 1984 and 1987 or 1988. 

Harper Lee’s To Kill a Mockingbird, published in 1960, takes place in 1935, and the two years preceding it, the seminal clue provided in the following comment by Atticus Finch during his summation and closing remarks during the rape trial of Tom Robinson: “There is a tendency in this year of grace, 1935, for certain people to use this phrase out of context, to satisfy all conditions.”  The reason we know that the story takes place in years preceding 1935 but leading up to that date is Scout’s descriptions of the passage of time, particularly with respect to the annual summer returns to Maycomb of Dill.