Each April, we celebrate Earth Day, a time to raise awareness of the various environmental challenges we face if we want to sustain our way of life. But where did Earth Day get its start?

Earth Day was first celebrated on April 22, 1970. It was the work of Gaylord Nelson, then a U.S. Senator from Wisconsin. Nelson was motivated to action by seeing the aftermath of a massive oil spill in Santa Barbara, California, the year before.

Inspired by the student anti-war movement, he realized that if he could infuse that energy with an emerging public consciousness about air and water pollution, it would force environmental protection onto the national political agenda.

That first celebration, which took the energy of the student anti-war movement and melded it with raising public consciousness of the threats of air and water pollution, led to the creation of the United States Environmental Protection Agency and the passage of the Clean Air, Clean Water, and Endangered Species Acts.

Coincidentally, the day before Earth Day, April 21, marks the birthday of John Muir, one of the original naturalists, who founded the Sierra Club.  Muir was born in Scotland and his parents immigrated to the United States when he was young. They bought a farm in Wisconsin, but Muir soon found himself wandering the American West, admiring the landscape. Various travels took him across the continent, but he grew particularly attached to the Yosemite Valley in California. His advocacy was largely responsible for its preservation as a national park. Check out Muir’s writings on nature and this detailed biography to learn more about the origins of environmentalism.