New York state Assemblymember Zohran Mamdani’s victory Tuesday over former Gov. Andrew Cuomo capped an astonishing anti-establishment campaign by a 34-year-old who was polling at 1% in January. But perhaps even more remarkably, Mamdani defeated the 67-year-old scion of a political dynasty as a proud socialist. Upon his inauguration in January, a member of the Democratic Socialists of America will preside over New York, the financial capital of America, and the country’s biggest and most influential city. Mamdani’s win constitutes the 21st century high-water mark for democratic socialists, after two surprisingly popular Democratic presidential campaigns by Sen. Bernie Sanders, I-Vt., pushed the Democratic policy platform to the left, inspired a wave of elections of socialists to Congress and state legislatures in the late 2010s and early 2020s, and helped trigger a dramatic surge in membership in the Democratic Socialists of America. Prior to Sanders’ 2016 presidential campaign, DSA’…