In Chapter One, Scout does give a brief history of her family and Maycomb. In that history, she does link Atticus' ancestor, Simon Finch, to General Andrew Jackson who fought in Alabama during the War of 1812. In discussing how and when the Finch's came to Alabama, Scout remarks:
I said if he wanted to take a broad view of the thing, it really began with Andrew Jackson. If General Jackson hadn’t run the Creeks up the creek, Simon Finch would never have paddled up the Alabama, and where would we be if he hadn’t?
Scout is referring to the Battle of Horseshoe Bend (part of the "Creek War" during the War of 1812) in which General Jackson drove the Creek Indians (Native Americans) "up the creek." Evidently, this battle paved the way for other settlers to come in, one being Simon Finch. General Jackson would later become president in 1828.
One historical reference regarding Calpurina is her church: First Purchase African M. E. Church. It was so named "First Purchase" because it was paid for by the earnings of the first freed slaves. Therefore, the church refers to abolition: the end of slavery.
On the level of Harper Lee's personal life, Atticus Finch is based on her (Lee's) father, Amasa Coleman Lee, who was also a lawyer who represented black defendants. The character of Dill was based on Lee's childhood friend, author Truman Capote.