New York City has had only one mayor who belonged to a socialist organization, David Dinkins, but almost no one knew it. His membership in Democratic Socialists of America (DSA) came at a time when the organization had little visibility, and it seemed to have nothing to do with how he conducted himself in office.

Ironically, the mayor who governed like a socialist of sorts — Fiorello La Guardia, who served 1934 to 1946 — was a lifelong Republican. Throughout his career, first in Congress and then as mayor, La Guardia had strong ties with those to his left. In 1924, he even successfully ran for reelection to the House of Representatives on the Socialist Party line, after his own party denied him the nomination because of his support for Progressive Party presidential candidate Robert M. La Follette. (Though LaGuardia asked to be listed in the House as a Progressive, the clerk put him down as a Socialist, leading the only actual Socialist in Congress, Milwaukee’s Victor L. Berger, to drolly declare the New Yorker “my whip.”)

More than his left-leaning alliances or his brief adventure as a nominal Socialist candidate, though, it was what La Guardia did in office that made him a model for what a socialist mayoralty might look like. Just a few months ago, that prospect appeared utterly improbable. But with the extraordinary rise of the candidacy of DSA member Zohran Mamdani, a look back at La Guardia’s time as mayor, and why he was able to accomplish so much, seems in order.