Every April 22, over a billion people around the world celebrate Earth Day by participating in neighborhood clean-up activities and environmental teach-ins. The planet's largest civic event began in 1970 when twenty million Americans poured out onto the streets to urge lawmakers to take action to protect the environment before it was too late. Now boasting over 50,000 partners in 195 countries, the Earth Day Network (EDN) has led to the establishment of numerous environmental policies, including the Clean Air Act, the Clean Water Act, and the Endangered Species Act.