First Earth Day Mobilizes 20 Million Americans, Launches Modern Environmental Movement

On April 22, 1970, approximately 20 million Americans—10% of the nation’s population—participated in the first Earth Day, the largest mass demonstration in American history to that point. Organized by Senator Gaylord Nelson of Wisconsin and coordinated by young activist Denis Hayes, Earth Day galvanized public support for environmental protection and catalyzed legislation including the creation of the Environmental Protection Agency and passage of the Clean Air Act, Clean Water Act, and Endangered Species Act.

Senator Nelson conceived of Earth Day after witnessing the devastating 1969 Santa Barbara oil spill. Inspired by the teach-in model of the antiwar movement, he announced plans for a national environmental teach-in in September 1969. Student activist Denis Hayes, recruited to coordinate the effort, built a network of organizers on college campuses and in communities nationwide.

The response exceeded all expectations. Across the country, schools held teach-ins, communities organized cleanup projects, and citizens marched in cities from New York to San Francisco. In New York City, Mayor John Lindsay closed Fifth Avenue to traffic as 100,000 people gathered. In Philadelphia, crowds flooded Fairmount Park. In Chicago, demonstrators protested the pollution-belching city incinerator.

Earth Day succeeded in uniting disparate constituencies: conservationists concerned with wilderness preservation, public health advocates focused on pollution, students from the antiwar movement, and suburban parents worried about their children’s health. The event demonstrated that environmental protection had broad popular support that crossed political, geographic, and demographic lines.

The political impact was immediate. Congress recessed so members could participate in home-district events. Nixon, who had previously shown limited interest in environmental issues, recognized the political significance. On December 2, 1970, he signed an executive order creating the Environmental Protection Agency to consolidate federal environmental programs. The Clean Air Act of 1970 passed with overwhelming bipartisan support. The Clean Water Act and Endangered Species Act followed.

Earth Day also provoked corporate backlash. Industries that had operated without environmental accountability began organizing to oppose regulation. The political mobilization of polluting industries would grow throughout the 1970s and accelerate in subsequent decades. Earth Day demonstrated both the power of grassroots environmental activism and the industry resistance it would face.