The first Earth Day was organized on April 22, 1970. The day has activated 20 million Americans from all walks of life and is widely credited with launching the modern environmental movement. The idea of having an Earth Day came to Earth Day founder Gaylord Nelson, then a U.S. Senator from Wisconsin, after witnessing the ravages of the 1969 massive oil spill in Santa Barbara, California. Today, each year more than 1 billion people participate in Earth Day activities to promote sustainable practices on environmental issues making it the largest civic observance in the world.