The history of Earth Day stems back to 1970, when 20 million Americans were inspired to demonstrate against the environmental impacts of 150 years of industrial development. Thousands of universities organized protests against the deterioration of the earth from oil spills, pollution, the loss of wilderness, and more, according to earthday.org.
Later in 1990, Earth Day went global with a campaign to drive recycling efforts around the world. Today, Earth Day is widely known as a day of action to promote change in both human behavior and policies for a cleaner world.