Between World War I and World War II , reformist Fiorello La Guardia was elected as the new mayor in 1933 and took office in 1934 , marking the fall of Tammany Hall after 80 years of dominating politics in New York City . The period between the World Wars saw the election of reformist mayor Fiorello La Guardia and the fall of Tammany Hall after 80 years of political dominance .