How have the writer's environment and her society influenced aspects of To Kill a Mockingbird?

A native of Alabama, Harper Lee sets To Kill a Mockingbird in the time and place with which she is familiar. She also models her characters after real people with whom she was acquainted.
Time
Born in 1926, Harper Lee sets the novel in the 1930s, the Depression era in which she lived as a child. This was also the time of the infamous Scottsboro Trials in Alabama, an interracial rape case, on which the trial of Tom Robinson seems to be loosely based. Also, biographies of Lee state that there was an event near her hometown in 1936 when she was ten years old that affected her greatly:

Before A.C. Lee became a title lawyer, he once defended two black men accused of murdering a white storekeeper. Both clients, a father and son, were hanged.

Place
Maycomb, Alabama, is the fictional name of Lee's hometown of Monroeville, Alabama. There is a courthouse in this town, where Lee's father handled cases as an attorney. Like Monroeville, Maycomb is in southern Alabama where Jim Crow laws were in effect in the 1930s. 
Characterization
There is no question that Dill Baker is modeled after Lee's childhood friend Truman Capote, who was from Mississippi and felt he was too weak for the boys while Lee was too tough for the girls. Like Scout with Dill, Lee often defended Truman.
Atticus Finch is modeled after Lee's father, who served in state government and was an attorney with more liberal ideas than the majority of citizens in Monroeville. He was the greatest parental force in Lee's life because her mother suffered from mental illness and stayed in the home.
Boo Radley also is based upon a real man. Truman Capote depicted him in his novel Other Voices, Other Rooms. About this man, Capote stated that in his novel, 

I had that same man living in the house that used to leave things in the trees, and then I took that out. He was a real man, and he lived just down the road from us.
https://www.arts.gov/national-initiatives/nea-big-read/to-kill-a-mockingbird

https://www.biography.com/writer/harper-lee

https://www.blackpast.org/african-american-history/scottsboro-boys-trial-and-defense-campaign-1931-1937/