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Why do we celebrate Earth Day on April 22?

Two sides of Earth from space - Western Hemisphere and Eastern Hemisphere - slightly pixelated.
This is NASA’s massive 3.2 gigapixel mosaic of … us. And we look good. It contains more than 36,000 individual photographs from the more than 50,000 images posted around the world on Earth Day, April 22, 2014. Image via NASA.

The very first Earth Day

The first Earth Day – April 22, 1970 – is sometimes said to have marked the beginning of the modern environmental movement.

It predates the U.S. Environmental Protection Agency, for example. It may be hard to imagine it now, but the first Earth Day was a revelation to many. It was a way not only of raising consciousness about environmental issues, but also of bringing together different groups that had been fighting separately against issues including oil spills, pollution from factories and power plants, raw sewage, toxic dumps, pesticides, the loss of wilderness, air pollution and more. At the first Earth Day in 1970, an estimated 20 million Americans participated. They took to the streets, parks, and auditoriums to demonstrate for a healthy environment and to participate in teach-ins.

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The April 22 date was selected in part because it fell between colleges’ spring break and final exams. And it was also when Arbor Day was observed, a day when people are encouraged to plant trees, which began in Nebraska in 1872.

Since 1970, many important environmental events have happened on Earth Day, including the signing of the Paris Agreement on April 22, 2016. is actively hosting its Earth Week Live digital event, this year’s theme is Planet vs. Plastics. You can participate in a series of Earth Day livestreams or see if there is an in-person event taking place near you. 

Rooted in Arbor Day

J. Sterling Morton was a Nebraska pioneer, a writer and editor for Nebraska’s first newspaper, and later secretary of the Nebraska Territory. He advocated planting trees in what was then a dusty and treeless prairie. At a State Board of Agriculture meeting in January 1872, Morton proposed that Nebraska citizens set aside April 10 as a day to plant trees. He suggested offering prizes as incentives for communities and organizations that planted the most trees. It’s said that Nebraskans planted about 1 million trees on that first Arbor Day in 1872. Planting trees remains a common practice in celebrating Earth Day today.

Ten years later, in 1882, Nebraska declared Arbor Day a legal holiday and the date was changed to Morton’s birthday, April 22. Arbor Day became a national observance, and it seemed natural to schedule April 22, 1970 – Arbor Day – as the first Earth Day.

Earth Day: Men planting a tree with girls in white lined up in background some year around 1900.
Here is Arbor Day – a day for planting trees and a precursor to Earth Day – at N.Y. Public School #4, 173rd St. & Fulton Ave., New York. Date unknown. Image via Library of Congress. Used with permission.

Uniting for environmental change

Kathleen Rogers is a former environmental attorney who has led the Earth Day Network since 2001. She frequently comments on environmental issues in the media (CNN, Fox News, NPR, Time, Washington Post, Los Angeles Times). She wrote of Earth Day:

Earth Day is now a global event each year, and we believe that more than 1 billion people in 192 countries now take part in what is the largest civic-focused day of action in the world.

It is a day of political action and civic participation. People march, sign petitions, meet with their elected officials, plant trees, clean up their towns and roads. Corporations and governments use it to make pledges and announce sustainability measures. Faith leaders, including Pope Francis, connect Earth Day with protecting God’s greatest creations, humans, biodiversity, and the planet that we all live on.

Want to participate? Sign up to join the Earth Day Movement.

Bottom line: Why do we celebrate Earth Day on April 22? The date stems from an earlier observance, Arbor Day. This year’s focus is “Planet vs. Plastics.”

Read more: Earth images from space: Our top 10

April 21, 2024

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