Zohran Kwame Mamdani won the Democratic mayoral primary last night. The socialist began this election with almost no name recognition. After his campaign left everything on the field, prepared for weeks of uncertainty and vote-counting complexity, Mamdani won so decisively last night that his main opponent, former governor Andrew Cuomo, a man who famously does not take no for an answer, conceded the race before 11 p.m.

Mamdani has moved quickly from candidate to historic phenomenon. His campaign and personality give New Yorkers hope. Speaking to a union crowd on the sidewalk at a poll site near Union Square yesterday, as temperatures climbed toward 100 degrees Fahrenheit, a beaming Mamdani, gamely wearing a “United Auto Workers for Zohran” T-shirt over a dress shirt, seemed to hardly break a sweat as motorists slowed their cars, honked their horns, and snapped pictures on their phones.

His victory is the biggest one yet for a socialist movement that has been building support steadily in New York City ever since Bernie Sanders ran for president in 2016. New York City’s Democratic Socialists of America (NYC-DSA) chapter, along with neighboring partners like Mid-Hudson Valley DSA, has won elected offices and legislative reforms, expanding renters’ rights, taxing the rich, and building publicly funded renewable energy, but before Mamdani’s campaign, had yet to become a mass movement.