Anti-nuclear protests reached a peak in the 1970s and 1980s and grew out of the environmental movement. Campaigns which captured national public attention involved the Calvert Cliffs Nuclear Power Plant, Seabrook Station Nuclear Power Plant, Diablo Canyon Power Plant, Shoreham Nuclear Power Plant, and Three Mile Island. On June 12, 1982, one million people demonstrated in New York City's Central Park against nuclear weapons and for an end to the cold war arms race. It was the largest anti-nuclear protest and the largest political demonstration in American history. International Day of Nuclear Disarmament protests were held on June 20, 1983 at 50 sites across the United States.