Ever since Democratic Socialists of America (DSA) emerged as a major force in New York politics, the group has been most successful in the city’s outer boroughs. Its adjacent strongholds in North Brooklyn and Western Queens are the binary star system around which much of the city’s left-wing politics have come to orbit. Neighborhoods like Astoria and Bed-Stuy routinely elect socialist candidates and are important sources of votes that can be marshaled on behalf of mainstream progressive candidates as well. As its power has burned brighter over the past five years, DSA’s influence has reached deeper into both boroughs — from Bay Ridge in South Brooklyn to Glen Oaks in East Queens — reaching the final frontiers controlled by the decaying county machines.

But socialist politics in New York City wasn’t always clustered on the western edge of Long Island. In 1919, five members of the Socialist Party won election to the state assembly; none of them were from Queens, and only two hailed from Brooklyn. One was from the Bronx, where DSA candidates have met a mixed reception in the modern era. The last two were from Manhattan: August Claessens, representing Harlem and Morningside Heights, and Louis Waldman, of the Lower East Side. Five years earlier, that neighborhood also chose the lawyer and union organizer Meyer London to represent them in Washington, one of only two people ever elected to Congress from the Socialist Party. The center of New York’s garment industry, the Lower East Side was a hotbed of labor militancy and radical politics.

Given this history, it’s notable that DSA never backed a candidate in Manhattan — until last month. In November, the group endorsed Illapa Sairitupac, a social worker from the Bowery and a longtime ecosocialist organizer, in his primary challenge to Brian Kavanagh, who represents Lower Manhattan and parts of North Brooklyn in the state senate. Though the field was already crowded, the dynamics of the race were upended recently when news broke that Yuh-Line Niou would not run for reelection in her overlapping state assembly district and would instead challenge Kavanagh herself. A darling of city progressives, Niou is certain to lock down major support from across New York’s left-of-center coalition and will make it difficult for another candidate to mount a credible challenge from the left.