Earth Day, the story

Earth Day 2008
April 22 marks the 38th anniversary of Earth Day, a day of celebration and activism intended to raise awareness of environmental issues. In 1970 a nationwide “Environmental Teach-In,” led by U.S. Senator Gaylord Nelson and Denis Hayes, helped organize around 20 million demonstrators to show support for a policy agenda focused on these concerns.

Source: the National Academies “WHATSNEWLIST”, Aoril 18, 2008