The national U.S. movement against nuclear power had its roots in New England in the 1970s. In 1974, activist Sam Lovejoy toppled a weather tower at the site of the proposed Montague Nuclear Power Plant in Western Massachusetts. The movement "reached critical mass" with the arrests at Seabrook Station Nuclear Power Plant on May 1, 1977, when 1,414 anti-nuclear activists from the Clamshell Alliance were arrested at the Seabrook site. Harvey Wasserman, Howard Morland, Paul Gunter and Frances Crowe played key roles in the movement.