One U.S. senator and a core of young organizers turned April 22, 1970, into the day the environmental movement was born.
On that day, 20 million Americans in 2,000 communities and 10,000 schools planted trees, cleaned up parks, buried cars in mock graves, marched, listened to speeches and protested how humans were messing up their world.
In New York, Marilyn Laurie, a young mother of two, convinced Mayor John Lindsay to close Fifth Avenue to cars and fill it with thousands of people to hear speakers. At the University of New Mexico, Arturo Sandoval led students and reporters from the three television networks through the dirt roads and adobe houses of Albuquerque's poorest neighborhood to smell the choking odor of the city sewer plant.
In Washington, D.C., 25-year-old Denis Hayes, the coordinator of the national event, shared the stage with senators and the rock-soul group The Chambers Brothers, who sang "Time Has Come Today." Earth Day was the brainchild of Sen. Gaylord Nelson, D-Wis., who came up with the idea of a national teach-in on the environment after 3 million gallons of oil spilled on the beaches of Santa Barbara and killed 10,000 seabirds in January 1969.
Nelson's idea gave birth to a green movement and a "green generation" that would be as powerful as the industrial revolution in shaping the future of civilization.
The timing of that first Earth Day turned out to be critical. Nelson picked April 22 because students would be back on campuses after spring break. It also fell between two other seminal national moments.
The nation had just shared the experience of watching on television the miraculous return of the damaged Apollo 13 capsule and its three astronauts on April 17, 1970.
That mood of national unity and celebration would be short-lived, however. President Richard Nixon's announcement that the U.S. had been secretly bombing Cambodia triggered mass protests and led to the May 4 killing of four students by Army National Guardsmen at Kent State University in Ohio. Many colleges closed their campuses.
"I don't think it would have been anywhere near as big had it come after Kent State," said Bill Mauk, an Idaho attorney who worked for Hayes organizing Earth Day in Washington.
Development following World War II had turned America's rivers into sewers and covered its cities with air pollution. Rachel Carson's 1962 book "Silent Spring" showed pesticides were poisoning wildlife and threatening human health.
Nuclear weapons tests had spread radioactive fallout to all parts of the Earth, and several environmental disasters in addition to the 1969 California oil spill caught the nation's attention. In June 1969, floating pollutants on the Cuyahoga River in Cleveland caught fire.
Hayes was heading to law school at Harvard in 1969 when he answered an ad looking to organize environmental teach-ins in New England. Hayes had been a prominent activist against the Vietnam War as the president of the Stanford student body.
He went to Nelson's office in Washington to interview -- and came away the national coordinator.
He gathered a staff of 20 idealistic young people to get information out to the thousands of colleges, schools and community groups that had expressed an interest in participating in Earth Day. This team included Sandoval, Mauk and Kent Conrad, a Stanford colleague from North Dakota who today is a U.S. senator.
"I thought it was very important to do what we were doing," Conrad said.
Nelson had prodded all three major television networks to provide expanded coverage of Earth Day. CBS did a special report, anchored by Walter Cronkite.
Sandoval convinced the networks that they'd get a great story if they followed him back to Albuquerque, where he'd been a Latino community activist.
Crews filmed colorful dancers in native costume, but they also got his message of environmental justice with the march through the city's poorest neighborhood to the sewer plant.
Nelson had wanted Earth Day to be a grassroots demonstration of wide public support for environmental issues. The senator, who had few allies in the 1960s, now had the public on his side.
"It was successful beyond his wildest dreams," Tia Nelson said of her father, who died in 2005. "There was no way to anticipate or imagine its impact."
Over the next decade, Congress passed the 28 major initiatives that became the foundation of the nation's environmental laws, including the Clean Air Act, the Clean Water Act, the Endangered Species Act, the Safe Drinking Water Act, the Occupational Health and Safety Act, the Toxic Substances Control Act and amendments strengthening the National Environmental Policy Act. Many passed in the first three years after Earth Day and were signed by Nixon.
In 1966, Nelson hadn't been able to find a single co-sponsor when he introduced a bill to ban the pesticide DDT, which was shown to cause the thinning of eggs of bald eagles, peregrine falcons and other of America's disappearing raptors.
By 1972, DDT had been banned.
Barker reports for the Idaho Statesman. He participated in the first Earth Day as a high school student and decided to go into environmental studies at Northland College in Ashland, Wis., where he got to know Sen. Gaylord Nelson. As a journalist, he's covered environmental issues for 35 years, the last 14 for the Statesman.