Answer:
1960's is when the book was written there were many major events one being the Civil Rights Protests.
Evidence: I ties into the story being loosely based on Lee's experience with racism which is the theme of the story and the storyline of the book takes place 30 years before it is written which made more of an impact on the events of the story since the 1930's major events where The Great Depression and the start of world war 2