Earth Day History.

Founded in 1970 as a day of education about environmental issues, Earth Day is now a globally celebrated holiday that is sometimes extended into Earth Week, a full seven days of events focused on green awareness. The brainchild of Senator Gaylord Nelson and inspired by the antiwar protests of the late 1960s, Earth Day was originally aimed at creating a mass environmental movement. It began as a "national teach-in on the environment" and was held on April 22 to maximize the number of students that could be reached on university campuses. By raising public awareness of air and water pollution, Nelson hoped to bring environmental causes into the national spotlight.

In 1990, Earth Day went global, with 200 million people in over 140 nations participating, according to the Earth Day Network (EDN), a nonprofit organization that coordinates Earth Day activities. In 2000, Earth Day focused on clean energy and involved hundreds of millions of people in 184 countries and 5,000 environmental groups, according to EDN. Activities ranged from a traveling, talking drum chain in Gabon, Africa, to a gathering of hundreds of thousands of people at the National Mall in Washington, D.C. Today, the Earth Day Network collaborates with more than 17,000 partners and organizations in 174 countries. According to EDN, more than 1 billion people are involved in Earth Day activities, making it "the largest secular civic event in the world."

 A highlight of the United Nations' Earth Day celebration in New York City is the ringing of the Peace Bell, a gift from Japan, at the exact moment of the vernal equinox.