Harper Lee's To Kill a Mockingbird takes place over slightly more than two years: Aside from the retrospective exposition in the opening pages, the story begins with the introduction of Dill's arrival in June 1933. We know this because Atticus states during his summation of the Tom Robinson trial that it is
"... in this year of grace, 1935..." (Chapter 20)
The story ends on Halloween night of 1935--in all, a period of about 28 months.
The novel is set in Maycomb, Alabama (a fictitious town based on Lee's hometown of Monroeville, Alabama), a small town and county seat of Maycomb County. Maycomb is located about 20 miles west of Finch's Landing (on the shore of the Alabama River), Atticus's birthplace. Maycomb is located
... awkwardly inland..., (Chapter 13)
a town that is more than 100 years old but which has changed little since before the Civil War.
There was nowhere to go, nothing to buy and no money to buy it with, nothing to see outside the boundaries of Maycomb County. (Chapter 1)
The Finch family lives on the "main residential street in town," though it is never named. The mysterious Radleys lived two doors down, their house jutting "into a sharp curve beyond our house."