On June 12, 1982, the largest protest in American history converged in New York, as an estimated one million protestors marched from Central Park to the United Nations to demand an end to nuclear weapons.

The rally and march were the culmination of a meeting 25 years earlier, amidst the Cold War between the United States and the Soviet Union, when activists met at the Overseas Press Club in Manhattan to discuss how to stop the proliferation of nuclear weapons. The group that emerged, “A National Committee for a Sane Nuclear Policy,” or “SANE,” inaugurated a widespread peace movement. New York City, with its longstanding pacifist tradition and key institutions of international relations, became the center of the disarmament movement.

The 1982 protest coincided with the second United Nations Special Session on Disarmament. The June 12 Rally Committee engaged in extensive planning with hundreds of organizations, an effort led in part by Leslie Cagan, also active in feminist and LGBT campaigns, African-American radical Jack O’Dell, and peace organizer Cora Weiss. Tensions surfaced over whether to emphasize freezing or reducing the number of nuclear weapons, and concerns over whether the march was truly inclusive. Yet the sheer number of people made June 12 a landmark day in the movement for nuclear disarmament.

New Yorkers remained at the forefront of local and global anti-nuclear campaigns through the 1980s, when President Ronald Reagan began to shift his position on nuclear munitions buildup and the Cold War came to an end. Still, the threat of nuclear arms continued to mobilize activists fearful of the weapons’ enormous power for destruction in New York and beyond.