In September 1969, at a conference in Seattle, Washington, U.S. Senator Gaylord Nelson of Wisconsin announced that in the spring of 1970 there would be a nationwide grassroots demonstration on the environment. Senator Nelson first proposed the nationwide environmental protest to thrust the environment onto the national agenda.” "It was a gamble," he recalls, "but it worked."

Five months before the first April 22 Earth Day, on Sunday, November 30, 1969, The New York Times carried a lengthy article by Gladwin Hill reporting on the rising tide of environmental events:

"Rising concern about the environmental crisis is sweeping the nation's campuses with an intensity that may be on its way to eclipsing student discontent over the war in Vietnam... a national day of observance of environmental problems... is being planned for next spring... when a nationwide environmental 'teach-in'... coordinated from the office of Senator Gaylord Nelson is planned...."

Senator Nelson also hired Denis Hayes as the coordinator.

Each year, the April 22 Earth Day marks the anniversary of the birth of the modern environmental movement in 1970. Among other things, 1970 in the United States brought with it the Kent State shootings, the advent of fiber optics, "Bridge over Troubled Water," Apollo 13, the Beatles' last album, the death of Jimi Hendrix, and the meltdown of fuel rods in the Savannah River nuclear plant near Aiken, South Carolina ~ an incident not acknowledged for 18 years. At the time, Americans were slurping leaded gas through massive V8 sedans. Industry belched out smoke and sludge with little fear of legal consequences or bad press. Air pollution was commonly accepted as the smell of prosperity. Environment was a word that appeared more often in spelling bees than on the evening news. But Earth Day 1970 turned that all around.

On April 22, 20 million Americans took to the streets, parks, and auditoriums to demonstrate for a healthy, sustainable environment. Denis Hayes, the national coordinator, and his youthful staff organized massive coast-to-coast rallies. Earth Day mobilized over 200 million people in 141 countries and lifted the status of environmental issues onto the world stage. 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, freeways, the loss of wilderness, and the extinction of wildlife suddenly realized they shared common values. Earth Day on April 22 in 1990 gave a huge boost to recycling efforts worldwide and helped pave the way for the 1992 United Nations Earth Summit in Rio de Janeiro.

As the millennium approached, Hayes agreed to spearhead another campaign, this time focused on global warming and a push for clean energy. The April 22 Earth Day in 2000 combined the big-picture feistiness of the first Earth Day with the international grassroots activism of Earth Day 1990. For 2000, Earth Day had the Internet to help link activists around the world. By the time April 22 rolled around, 5,000 environmental groups around the world were on board, reaching out to hundreds of millions of people in a record 184 countries. Events varied: A talking drum chain traveled from village to village in Gabon, Africa, for example, while hundreds of thousands of people gathered on the National Mall in Washington, D.C., USA.

Earth Day 2000 sent the message loud and clear that citizens the world 'round wanted quick and decisive action on clean energy. Earth Day 2007 was one of the largest Earth Days to date, with an estimated billion people participating in the activities in thousands of places like Kiev, Ukraine; Caracas, Venezuela; Tuvalu; Manila, Philippines; Togo; Madrid, Spain; London; and New York.

Founded by the organizers of the first April 22 Earth Day in 1970, Earth Day Network promotes environmental citizenship and year round progressive action worldwide. Earth Day Network is a driving force steering environmental awareness around the world. Through Earth Day Network, activists connect change in local, national, and global policies. Earth Day Network’s international network reaches over 17,000 organizations in 174 countries, while the domestic program engages 5,000 groups and over 25,000 educators coordinating millions of community development and environmental protection activities throughout the year.

Earth Day is the only event celebrated simultaneously around the globe by people of all backgrounds, faiths and nationalities. More than a half billion people participate in Earth Day Network campaigns every year.