When Michael Bloomberg handed over the city to Bill de Blasio, New York and the country were experiencing record levels of income inequality. De Blasio was the first progressive elected to City Hall in twenty years. Invoking Fiorello La Guardia's name, he pledged to improve the lives of those marginalized by poverty and prejudice. Unlike La Guardia, de Blasio did not have allies in Washington like President Franklin D. Roosevelt who could effectively support his progressive agenda.

As de Blasio approached the end of his first term, the situation worsened, with Donald Trump in the White...