Question: Who was New York's mayor during the book's historical period?

Knowledge 1: To Kill a Mockingbird
The story takes place during three years (1933–35) of the Great Depression in the fictional "tired old town" of Maycomb, Alabama, the seat of Maycomb County. It focuses on six-year-old Jean Louise Finch (Scout), who lives with her older brother, Jem, and their widowed father, Atticus, a middle-aged lawyer. Jem and Scout befriend a boy named Dill, who visits Maycomb to stay with his aunt each summer. The three children are terrified of, and fascinated by, their neighbor, the reclusive Arthur "Boo" Radley. The adults of Maycomb are hesitant to talk about Boo, and, for many years few have seen him. The children feed one another's imagination with rumors about his appearance and reasons for remaining hidden, and they fantasize about how to get him out of his house. After two summers of friendship with Dill, Scout and Jem find that someone leaves them small gifts in a tree outside the Radley place. Several times the mysterious Boo makes gestures of affection to the children, but, to their disappointment, he never appears in person. [SEP] Knowledge 2: New York City
New York became the most populous urbanized area in the world in the early 1920s, overtaking London. The metropolitan area surpassed the 10 million mark in the early 1930s, becoming the first megacity in human history. The difficult years of the Great Depression saw the election of reformer Fiorello La Guardia as mayor and the fall of Tammany Hall after eighty years of political dominance.
Knowledge 1: New York City
New York became the most populous urbanized area in the world in the early 1920s, overtaking London. The metropolitan area surpassed the 10 million mark in the early 1930s, becoming the first megacity in human history. The difficult years of the Great Depression saw the election of reformer Fiorello La Guardia as mayor and the fall of Tammany Hall after eighty years of political dominance. [SEP] Knowledge 2: William Lafayette Strong
William Lafayette Strong (March 22, 1827 -- November 2, 1900) was the 90th Mayor of New York City from 1895 to 1897. He was the last mayor of New York City before the Consolidation of the City of Greater New York on January 1, 1898.
Knowledge 1: To Kill a Mockingbird
The story takes place during three years (1933–35) of the Great Depression in the fictional "tired old town" of Maycomb, Alabama, the seat of Maycomb County. It focuses on six-year-old Jean Louise Finch (Scout), who lives with her older brother, Jem, and their widowed father, Atticus, a middle-aged lawyer. Jem and Scout befriend a boy named Dill, who visits Maycomb to stay with his aunt each summer. The three children are terrified of, and fascinated by, their neighbor, the reclusive Arthur "Boo" Radley. The adults of Maycomb are hesitant to talk about Boo, and, for many years few have seen him. The children feed one another's imagination with rumors about his appearance and reasons for remaining hidden, and they fantasize about how to get him out of his house. After two summers of friendship with Dill, Scout and Jem find that someone leaves them small gifts in a tree outside the Radley place. Several times the mysterious Boo makes gestures of affection to the children, but, to their disappointment, he never appears in person. [SEP] Knowledge 2: 2017 New York City mayoral election
An election for Mayor of New York City was held on November 7, 2017. Bill de Blasio, the incumbent mayor, won re-election to a second term.

Answer: Fiorello La Guardia