Holiday Calendar

Earth Day

Next celebratedThursday, April 22, 2027

An environmental observance held on April 22 that promotes conservation, environmental awareness, and action through teach-ins, cleanups, and demonstrations worldwide.

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Last updated February 26, 2026 · by the Holiday Calendar TeamHave an update or spot an error?
YEARLY DATEApril 22
OBSERVED INInternationally
CATEGORYNature
SUBCATEGORYConservation
ORIGIN

Individual Initiative

FOUNDING ENTITY
United States Senator Gaylord Nelson
FIRST OBSERVED
1970
Gaylord Nelson recruited Denis Hayes to organize the first Earth Day on April 22, 1970, which drew an estimated 20 million Americans.
HOW THE HOLIDAY CAME TO BE

A senator borrowed a tactic from the anti-war campus and aimed it at pollution.

Wisconsin Senator Gaylord Nelson conceived Earth Day after the January 1969 Santa Barbara oil spill, adapting the anti-war campus teach-in to the environment. He recruited activist Denis Hayes as national coordinator and named Republican Congressman Pete McCloskey his co-chair, and the first Earth Day, on April 22, 1970, drew an estimated 20 million Americans.

Read the U.S. Senate historyvia U.S. Senate Historical Office
INTRO

The day 20 million Americans went outside at once

On a Wednesday in the spring of 1970, an estimated 20 million Americans walked out of offices, schools, and homes for a single environmental demonstration. That was roughly one in ten people in the country at the time.

Encyclopaedia Britannica calls it the largest single-day protest in American history. What it became is now routine: a worldwide date marked by cleanups, teach-ins, and tree plantings every April 22.

What is easy to forget is how unlikely that turnout was, and how deliberately it was built to cross party lines rather than divide along them.

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ORIGINS

Earth Day history

INTRODUCTION

A U.S. senator from Wisconsin had been worrying about pollution for years. Gaylord Nelson saw the spill and its aftermath, and he kept turning over how to make the public and Congress care at the same time.

CHAPTER 01

An idea borrowed mid-flight

The answer came from an unlikely source. Flying back east, Nelson read a magazine article about the anti-Vietnam-War teach-ins spreading across college campuses, according to the U.S. Senate Historical Office.

He decided the teach-in model could work for the environment. The plan was a national day of education on college campuses, scaled outward to everyone else.

CHAPTER 02

Built to be bipartisan

Nelson, a Democrat, did not keep the project to one side. He recruited a young activist named Denis Hayes to run it, and he named Pete McCloskey, a conservation-minded Republican congressman, as his co-chair.

Hayes built a national staff of 85 and chose April 22, a weekday that fell between spring break and final exams, to catch the most students. The name they settled on, Earth Day, drew immediate press.

CHAPTER 03

What April 22 set in motion

The turnout reshaped the politics of the issue almost at once. By the end of 1970, the first Earth Day had helped spur the creation of the U.S. Environmental Protection Agency and the passage of the Clean Air Act, with the Clean Water Act following in 1972.

In 1990, Hayes organized a global edition that, by EarthDay.org's count, mobilized 200 million people in 141 countries. Earth Day has been international ever since, and in 2009 the United Nations gave April 22 a second name: International Mother Earth Day. ]]>

BY THE NUMBERS

Earth Day by the Numbers

20M
Americans at the first Earth Day, 1970
200M
People in the first global Earth Day, 1990
141
Countries in the 1990 global Earth Day
~1B
People observing Earth Day worldwide today
~1°C
Global surface warming since the late 1800s (NASA)

TIMELINE

Timeline

Silent Spring is published

Rachel Carson's book on pesticides becomes a bestseller and helps raise the public environmental awareness that set the stage for Earth Day.

The Santa Barbara oil spill

A major blowout off the California coast covers miles of beaches with crude and helps move Senator Gaylord Nelson to act.

The first Earth Day

On April 22, an estimated 20 million Americans take part in the demonstration organized by Nelson, Denis Hayes, and Pete McCloskey.

The EPA and the Clean Air Act

By the end of the year, the first Earth Day has helped spur the creation of the EPA and the passage of the Clean Air Act.

Earth Day goes global

Denis Hayes organizes the first worldwide Earth Day, mobilizing 200 million people across 141 countries.

The UN names April 22

The General Assembly, in a Bolivia-led resolution adopted by consensus, proclaims April 22 International Mother Earth Day.
My primary objective in planning Earth Day was to show the political leadership of the Nation that there was broad and deep support for the environmental movement.
Gaylord NelsonEarth Day founder, EPA Journal, 1980

WHY THIS DAY MATTERS

Why Earth Day Matters

LEGISLATION

A diffuse public concern got one date lawmakers could not ignore.

The months around the first Earth Day saw the creation of the EPA and the Clean Air Act, with the Clean Water Act following in 1972. The observance gave a diffuse public concern a single, visible date that lawmakers could not ignore.

SCALE

It became a worldwide observance

What began as a U.S. event went global in 1990 and is now marked across much of the world. EarthDay.org describes Earth Day as one of the largest secular observances on the planet.

RECOGNITION

The United Nations adopted the date

In 2009 the UN General Assembly proclaimed April 22 International Mother Earth Day. That gave the grassroots American date a formal place on the international calendar.

GOOD TO KNOW

Surprising facts about Earth Day

The Lenin's-birthday story is a myth

A long-running rumor claims April 22 was chosen to honor Vladimir Lenin's birthday. Snopes rates the claim false; the date was set to fall between spring break and final exams.

The co-chair was a Republican

Democrat Gaylord Nelson named conservation-minded Republican Congressman Pete McCloskey as Earth Day's co-chair, a deliberate move to keep the cause from becoming a partisan one.

The Paris Agreement opened on Earth Day

On April 22, 2016, the Paris climate agreement opened for signature at UN Headquarters, where 175 countries signed on the first day.

A rival Earth Day was proposed for the equinox

Peace activist John McConnell pushed a separate Earth Day for the first day of spring, March 21. The April 22 version is the one that took hold.

The first Earth Day reached about 10% of the country

The roughly 20 million participants in 1970 amounted to about one in ten Americans, on 2,000 college campuses and at 10,000 schools.

GET INVOLVED

How to Observe Earth Day

EDITOR'S PICK

Join a local cleanup

Cleanups are one of the most common Earth Day activities worldwide. Find an organized event near you through the official EarthDay.org network or a local park or river group.

READ

Read the founder's own account

Gaylord Nelson reflected on what the first Earth Day meant in a 1980 EPA Journal essay. You can read his words in the EPA archive.

PLANT

Plant or care for a tree

Tree plantings are a long-standing way to mark the day. A single tree on your street or a sapling at a community planting both fit the observance.

LEARN

Learn what the science bodies report

Earth Day's modern themes track climate research. Read the plain-language evidence pages from NASA rather than secondhand summaries.

LOOK

Look up your area's history

Many cities held their own 1970 rallies. Check a local newspaper archive or library to see how your community marked the first Earth Day.

Test your knowledge

How well do you know Earth Day?

1 / 8

On what date is Earth Day observed?

Answer

Earth Day is observed on April 22 every year, in the United States and internationally.

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