Earth Day 1970 was a nationwide grassroots demonstration in the United States that helped raise public awareness of environmental issues. It was founded by Senator Gaylord Nelson as an environmental teach-in in response to issues like air and water pollution. On the first Earth Day in 1970, an estimated 20 million Americans participated in rallies and events across the country. This widespread participation and support from people across demographics helped push for the creation of the Environmental Protection Agency and the passage of new environmental laws and regulations in the United States.