Responding to growing concerns about the environment, then-U.S. Senator Gaylord Nelson, (D-WI), called for an Environmental Teach-in or Earth Day to be held on April 22, 1970. More than 20 million people took part.
More than 500 million people in 175 countries now observe Earth Day each year.
Nelson modeled Earth Day on the increasingly effective Vietnam War protests of the time. The first Earth Day had participants in 2,000 colleges and universities; in 10,000 elementary, junior high and high schools and in hundreds of communities
The first Earth Day led to the creation of the Environmental Protection Agency and the passage of the Clean Air, Clean Water, and Endangered Species acts.
- Source: earthday.org