How does TKAMB show societal change throughout the story?

Unfortunately there is very little societal change through the story. Tom Robinson is convicted of a crime he did not do. All evidence points that it was actually Mr. Ewell that raped his own daughter yet Tom is found guilty. There is however a glimmer of hope. Mr. Cunningham held the jury for a long time insisting that Tom is not guilty. Recalls that Mr.Cunningham had previously lead a mob to lynch Tom Robinson. Mr. Underwood writes an article in the newspaper denouncing the verdict. All of white Maycomb knew who was really guilty and must forever reconcile their bigotry with the death of an innocent man.