Why do you think Harper Lee mentions slaves in early chapter one in To Kill a Mockingbird?

To Kill a Mockingbird is a book about racism. Race-based slavery is the epitome of racism and because slavery was of economic benefit to certain people, it helped to prolong racial tension long after it had been abolished. By referencing slavery, Harper Lee is setting the background and tone for her book. Please remember that the book takes place during the Great Depression, when racial tensions were higher than they were today and some people could still remember slavery.