Earth Day was founded in 1970 as a way to increase public awareness about environmental issues. Each year on April 22, millions of people worldwide celebrate the day with rallies, clean-up events and educational programs.Watch the video above to learn more.Earth Day was founded by environmentalist and former Wisconsin Sen. Gaylord Nelson. Nelson, a leading figure in the fight to protect the environment, was awarded the Presidential Medal of Freedom in 1995. In his speech marking the 25th anniversary of Earth Day in 1995, he said, "The opportunity for a gradual but complete break with our destructive environmental history and a new beginning is at hand…. We can measure up to the challenge if we have the will to do so — that is the only question. I am optimistic that this generation will have the foresight and the will to begin the task of forging a sustainable society."Earth Day celebrations are popular among young people, specifically college students. In fact, Nelson chose the date of April 22 because it falls between many students’ spring break and final exams.The first Earth Day succeeded in raising environmental awareness in America, and in July of 1970, the Environmental Protection Agency was established to regulate and enforce national pollution laws.Earth Day also inspired the passing of legislation such as the Clean Water Act, Endangered Species Act, National Environmental Education Act and more.Earth Day has been celebrated on different days by different groups around the world. The United Nations officially celebrates it on the vernal equinox, which usually occurs around March 21.