Millions will observe Earth Day on Wednesday, building on a movement that started in the United States and has since spread worldwide. The Associated Press describes how the day traces its roots to rising concern about pollution in the 1960s and to a student “teach-in” idea that organizers expanded from college campuses to broader public events.
Earth Day’s early momentum is tied to the public impact of Rachel Carson’s 1962 book “Silent Spring,” which highlighted the damaging effects of the pesticide DDT on the food chain. The AP also points to a shift from awareness to organizing: a U.S. senator from Wisconsin, Democrat Gaylord Nelson, developed the concept that would become Earth Day after a massive offshore oil spill in 1969 sent millions of gallons onto the Southern California coast.
Nelson’s proposal built on a model already familiar to students at the time—teach-ins held at some college campuses to oppose the Vietnam War. The Associated Press reports that Nelson, along with activists including Denis Hayes, worked to broaden the idea beyond campus events, scheduling activities across the country and adopting the Earth Day name for the effort.
Organizers later chose April 22, 1970 for the first Earth Day, according to history shared by EarthDay.org, where Hayes remains board chair emeritus. The organization says the date was selected because it fell on a weekday between spring break and final exams, aiming to attract as many students as possible.
Earth Day itself is not a federal holiday, but many groups still use the day to organize volunteer events with environmental goals. The Associated Press notes that people can find listings of events worldwide or register their own at EarthDay.org.
As the observance expanded, Earth Day became linked to political and policy changes as well as to grassroots organizing. The AP reports that the large public response to the first Earth Day helped pressure the U.S. Congress to take more steps to address pollution, contributing to landmark legislation including the Clean Air Act and the Clean Water Act, and that in later years Earth Day expanded into a global event that claims to have motivated action in more than 192 countries.
In 2000, Earth Day began focusing more directly on climate change, a problem described as increasingly urgent in recent years. This year, the theme centers around the slogan “Our Power, Our Planet,” which encourages collective action against environmental impacts.
The day’s through-line—from Carson’s alarm about pesticide harm to Nelson’s student teach-in approach to Hayes and others’ push for broader participation—remains the same: mobilize public attention, then convert it into sustained action.