Earth Day - April 22, the modern environmental observance that started with a 1969 teach-in and now reaches more than 190 countries
Earth Day on April 22 is the annual international observance of the modern environmental movement, founded in 1970 by US Senator Gaylord Nelson and celebrated in more than 190 countries. It falls during World Earth Week and overlaps with the March equinox Earth Day observed by the United Nations.
International observancePublished October 12, 2026
- When
- April
- Frequency
- Same date every year
- Days off
- Varies by country
- Public status
- Varies by country; consult local government gazette
Earth Day on April 22 is the annual international anchor of the modern environmental movement. Founded in 1970 by US Senator Gaylord Nelson, observed in more than 190 countries, and not a UN-proclaimed day in its own right - though the UN observes International Mother Earth Day on the March equinox. The April 22 observance is the larger and longer-running of the two.
The one-line summary
International environmental observance on April 22, founded in 1970 by US Senator Gaylord Nelson. Observed in 190+ countries. Not a public holiday anywhere except Bolivia and a few sub-national jurisdictions. Distinguished from the UN International Mother Earth Day on the March equinox.
Origin
Earth Day was founded in 1970 by US Senator Gaylord Nelson of Wisconsin, a Democrat who had been working since 1962 to bring environmental issues into the national political conversation. After the 1969 Santa Barbara oil spill off the California coast, Nelson recruited Denis Hayes, a young activist and Harvard Law student, to organise a nationwide teach-in for April 22, 1970.
The first Earth Day drew an estimated 20 million Americans - at the time the largest civic event in human history. The teach-in format - speakers, panels, teach-outs, and coordinated local actions - was borrowed from the anti-Vietnam War movement, which had used similar tactics in 1969. April 22 was chosen because it fell between spring break and final exams at most US universities, maximising student turnout.
The 1970 teach-in
The first Earth Day was organised as 1,500+ simultaneous teach-ins across the United States. Speakers included Senator Nelson, Senator Edmund Muskie, Representative Pete McCloskey, biologist Barry Commoner, and conservationist David Brower. Teach-ins covered air and water pollution, oil spills, nuclear power, pesticide use, wildlife conservation, and population growth. The New York City teach-in drew an estimated 100,000 people to Union Square; the Philadelphia teach-in drew 50,000; the Washington DC teach-in drew 25,000.
The first Earth Day catalysed a wave of US environmental legislation in the early 1970s, including the National Environmental Policy Act (signed into law January 1, 1970, just before the first Earth Day), the Clean Air Act (1970), the Clean Water Act (1972), the Endangered Species Act (1973), and the creation of the US Environmental Protection Agency (1970).
The 1990s expansion
Earth Day went global in 1990, when Denis Hayes organised a second Earth Day teach-in that drew an estimated 200 million participants in 141 countries. The 1990 observance established the April 22 date as the international anchor for environmental civic action. The 1995 observance focused on consumer recycling. The 2000 observance focused on clean energy and climate change.
Earthday.org (originally the Earth Day Network) was founded in 1970 as the National Earth Day Committee, renamed the Earth Day Network in 1990, and renamed Earthday.org in 2017. The organisation is based in Washington DC and coordinates the international observance, including the annual theme campaign and the Earth Day Live digital event.
UN observance
The UN General Assembly proclaimed International Mother Earth Day on the March equinox (around March 20) in Resolution 63/278 (2009). The March equinox date was chosen because it marks the astronomical start of spring in the Northern Hemisphere and the astronomical start of autumn in the Southern Hemisphere - a globally shared seasonal moment that emphasises Earth\'s climate as a single interconnected system.
The UN observance and the April 22 civic observance run as parallel campaigns. The April 22 date is older and larger; the March equinox date is the formal intergovernmental anchor. The two are sometimes jointly called "World Earth Week" or "Earth Week" in the calendar of environmental organisations, with the days and weeks around each being treated as part of a single continuous campaign window.
How it is observed
Earth Day is observed through clean-ups, tree-planting, school assemblies, marches, corporate ESG announcements, and policy events. Major organisations including Earthday.org, the World Wildlife Fund, 350.org, Friends of the Earth, and Greenpeace coordinate campaigns. Schools in the US, UK, India, Brazil, and Germany run Earth Day curricula. Earthday.org has run an Earth Day Live digital event since 2020, reaching tens of millions of viewers each year.
Many cities use the day to publish environmental progress reports, announce new climate policies, or open new parks and green spaces. Corporations including Microsoft, Google, Salesforce, Apple, and Amazon have used the day to announce climate commitments, sustainability reports, and renewable energy investments.
Annual themes
Earthday.org publishes a theme each year. Recent themes have included "Restore Our Earth" (2021), "Invest in Our Planet" (2022), "Trees for the Earth" (the 50th anniversary campaign running 2016-2020), and "Planet vs. Plastics" (2024). The 2025 theme was "Our Power, Our Planet", focused on renewable energy. The 2026 theme was not announced as of January 2026.
Legal status
Earth Day is not a US federal holiday and is not a public holiday in most countries. Bolivia observes April 22 as a public holiday (Dia de la Madre Tierra) under Law 071 of 2010, which also recognises the rights of Mother Earth. A handful of other jurisdictions mark the day with public sector closures, including parts of Australia\'s ACT and some US states and school districts.
Where it is contested
Earth Day is broadly uncontested as an environmental moment. Critics from within the environmental movement have noted that the day\'s reliance on corporate ESG announcements can enable greenwashing - major polluters using Earth Day as a platform for climate commitments that are not subsequently delivered. Earthday.org and 350.org have addressed these critiques by running science-based accountability campaigns alongside corporate announcements.
Earth Day by the numbers
Sources
- Earthday.org: earthday.org
- UN International Mother Earth Day: un.org/en/observances/earth-day
- Denis Hayes on the 1970 Earth Day: earthday.org/history
- EPA on the founding of the EPA: epa.gov/history