What is the approximate date of the trial in Chapter 20 of "To Kill a Mockingbird"?
Although there is no specific date given for the Tom Robinson trial in Harper Lee's novel, To Kill a Mockingbird, we do finally learn the exact year in which the story takes place. There are other references to historical events which determines that it is definitely the early- to mid-1930s, but Atticus specifically tells us the year during his summation to the jury.
"There is a tendency in this year of grace, 1935..."
We also know that it is probably July or August, since Atticus relates that he has received an extension until "summer" and that Jem and Scout are out of school. Shortly after the end of school, Scout receives a letter from Dill saying he will not be coming to Maycomb since "he had a new father." Then,
... the state legislature was called into emergency session and Atticus left us for two weeks.
Atticus returns, and Dill makes a surprise visit. "We had a week of peace together," Scout tells us. Then, on Sunday, the day before the trial, Atticus makes his stand at the jail before the lynch mob. So, assuming that school in Alabama lets out in early- to mid-June, by adding the two weeks that Atticus was absent plus the "week of peace" and several days in between, this places the trial no sooner than early July 1935. It, of course, could be as late as August.
Tom Robinson's trial takes place in 1935. This trial is fashioned after two trials: The first one is that of the Scottsboro Boys in Alabama, a trial which took place in 1931 and a trial in which Harper Lee's father was involved.
Around the time of the 1920's, Mr. Amasa Coleman Lee, the father of Harper Lee, was involved in a trial of two black men, father and son, who were charged with having murdered a white storekeeper. These men were found guilty and hanged. Along with the trial of the Scottsboro Boys, this other Alabama trial served as a model for that of Tom Robinson in To Kill a Mockingbird.
The trial of Robinson in 1935 takes place during the children's summer vacation because they are able to be in court most of the day. Also, Scout narrates that although it is hot inside the courtroom, she is surprised when Atticus
...unbuttoned his vest, unbuttoned his collar, loosened his tie, and took off his coat"
as he prepares to address the jury. Further, he pulls out his handkerchief and wipes his glasses and face that is "shining."