What is Earth Day and how did it start? Wikipedia tells us:
Earth Day proved extremely popular in the United States and around the world. The first Earth Day, in 1970, had participants and celebrants in two thousand colleges and universities, roughly ten thousand primary and secondary schools, and hundreds of communities across the United States. More importantly, it “brought 20 million Americans out into the spring sunshine for peaceful demonstrations in favor of environmental reform.”
Senator Nelson directly credited the first Earth Day with persuading U.S. politicians that environmental legislation had a substantial, lasting constituency. Many important laws were passed by the Congress in the wake of the 1970 Earth Day, including the Clean Air Act, laws to protect drinking water, wild lands and the ocean.
Now observed in 175 countries, and coordinated by the non-profit Earth Day Network, www.earthday.org, Earth Day is the largest secular holiday in the world.