Earth Day marked the beginning of the modern environmental movement. Approximately 20 million Americans participated. Thousands of colleges and universities organized protests against the deterioration of the environment. Groups that had been fighting against oil spills, polluting factories and power plants, raw sewage, toxic dumps, pesticides, Freeway and expressway revolts, the loss of wilderness, and the extinction  of wildlife  suddenly realized they shared common values.

Senator Gaylord Nelson of Wisconsin announced his idea for a nationwide teach-in day on the environment in a speech to a fledgling conservation group in Seattle on 20 September 1969, and then again six days later in Atlantic City to a meeting of the United Auto Workers. Senator Nelson hoped that a grassroots outcry about environmental issues might prove to Washington, D.C. just how distressed Americans were in every constituency.

According to Senator Nelson, “Earth Day worked because of the spontaneous response at the grassroots level. We had neither the time nor resources to organize 20 million demonstrators and the thousands of schools and local communities that participated. That was the remarkable thing about Earth Day…”

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