Responding to widespread environmental degradation, Gaylord Nelson, a United States Senator from Wisconsin, called for an environmental teach-in, or Earth Day, to be held on April 22, 1970. Over 20 million people participated that year, and Earth Day is now observed on April 22 each year by more than 500 million people and several national governments in 175 countries.

Senator Nelson, an environmental activist, took a leading role in organizing the celebration, hoping to demonstrate popular political support for an environmental agenda. He modeled it on the highly effectiveVietnam War teach-ins of the time. Earth Day was first proposed in a prospectus to JFK written by Fred Dutton.However, Nelson decided against much of Dutton's top-down approach, favoring a decentralized, grassroots effort in which each community shaped their action around local concerns.

Nelson had conceived the idea for Earth Day following a trip he took to Santa Barbara right after the horrific oil spill off the coast in 1969. Outraged by the devastation and Washington political inertia, Nelson proposed a national teach-in on the environment to be observed by every university campus in the U.S.

I am convinced that all we need to do to bring an overwhelming insistence of the new generation that we stem the tide of environmental disaster is to present the facts clearly and dramatically. To marshal such an effort, I am proposing a national teach-in on the crisis of the environment to be held next spring on every university campus across the Nation. The crisis is so imminent, in my opinion, that every university should set aside 1 day in the school year-the same day across the Nation-for the teach-in.

One of the organizers of the event said:

"We're going to be focusing an enormous amount of public interest on a whole, wide range of environmental events, hopefully in such a manner that it's going to be drawing the interrelationships between them and, getting people to look at the whole thing as one consistent kind of picture, a picture of a society that's rapidly going in the wrong direction that has to be stopped and turned around.

"It's going to be an enormous affair, I think. We have groups operating now in about 12,000 high schools, 2,000 colleges and universities and a couple of thousand other community groups. It's safe to say I think that the number of people who will be participating in one way or another is going to be ranging in the millions."

Nelson announced his idea for a nationwide teach-in day on the environment in a speech to a fledgling conservation group in Seattle on September 20, 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. Senator Nelson invited Republican Representative Paul N “Pete” McCloskey to serve as his co-chair and they incorporated a new non-profit organization, environmental Teach-In, Inc., to stimulate participation across the country. Both continued to give speeches plugging the event.

On September 29, 1969, in a long, front-page New York Times article, Gladwin Hill wrote:

"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, analogous to the mass demonstrations on Vietnam, is being planned for next spring, when a nationwide environmental 'teach-in'...coordinated from the office of Senator Gaylord Nelson is planned...."

Denis Hayes, a Harvard graduate student, read the NYT article and traveled to Washington to get involved. He had been student body president and a campus activist at Stanford University in McCloskey’s district and where Teach-In board member Paul Ehrlich was a professor. He thought he might be asked to organize Boston. Instead, Nelson eventually asked Hayes to drop out of Harvard, assemble a staff, and direct the effort to organize the United States. Hayes would go on to become a widely recognized environmental advocate.

Hayes recruited a handful of young college graduates to come to Washington, D.C. and began to plan what would become the first Earth Day.

Nelson's suggestion was difficult to implement, as the Earth Day movement proved to be autonomous with no central governing body. As Senator Nelson attests, it simply grew on its own:

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. It organized itself.

Official Earth Week logo that was used as the backdrop for the prime time CBS News Special Report with Walter Cronkite about Earth Day 1970.

On April 22, 1970, 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 air pollution suddenly realized they shared common values.

Media coverage of the first Earth Day included a One-Hour Prime-time CBS News Special Report called "Earth Day: A Question of Survival," with correspondents reporting from a dozen major cities across the country, and narrated by Walter Cronkite (whose backdrop was the Earth Week Committee of Philadelphia's logo).

Pete Seeger was a keynote speaker and performer at the event held in Washington DC. Paul Newman and Ali McGraw attended the event held in New York City.

Sumber  http://en.wikipedia.org