In the book To Kill a Mockingbird, how long is the action of the novel?

Harper Lee's To Kill a
Mockingbird takes place over a two year period (or slightly longer). Scout,
the narrator, begins the story when she is six years old and is eight when the story
ends. The years in which the story takes place are 1933-1935. We know this because
Atticus comments during his summation in the Tom Robinson trial
that

"... in
this year of grace,
1935..."

Two previous summers
have passed since the arrival of Dill, which puts his first appearance as 1933. The
story ends on Halloween of 1935, so the total time frame is about 28 months. Of course,
the novel opens with a reminiscence by a much older Scout, at an undisclosed time in the
future. She mentions on the first page how she and Jem still consult Atticus
since

We were
far too old to settle an argument with a
fist-fight.

So, we also find
that Jem and Scout lived to adulthood and that their seemingly elderly father was still
alive to give them his regular doses of good advice.