Earth Day

Earth Day is April 22 every year, so Earth Day 2027 falls on a Thursday. It began on April 22, 1970, when about 20 million Americans, roughly one in ten people in the country, joined teach-ins, rallies and cleanups. That first Earth Day helped lead to the Environmental Protection Agency and a string of federal environmental laws. It is an observance, not a federal holiday.

What Earth Day Is

Earth Day is an annual day of environmental education and action. In practice it means school lessons, park and beach cleanups, tree plantings, community fairs and announcements from governments and companies about environmental plans. The nonprofit EARTHDAY.ORG coordinates a global campaign around the date each year.

The day matters historically because it worked. Before 1970, as the EPA puts it, the country had no EPA, no Clean Air Act and no Clean Water Act, and factories could legally release toxic pollution. Within a few years of the first Earth Day, all three existed.

Earth Day History: How the First Earth Day Came Together

The pressure building in the 1960s

Public worry about pollution had been growing for a decade. Rachel Carson’s Silent Spring, published in 1962, criticized the heavy use of pesticides and sold more than 500,000 copies in 24 countries. In January 1969, a massive spill from an offshore oil rig near Santa Barbara, California, fouled the beaches. Around the same time, the Cuyahoga River in Ohio caught fire, a vivid sign of how polluted American waterways had become.

Gaylord Nelson’s teach-in

Sen. Gaylord Nelson of Wisconsin saw the Santa Barbara spill and wanted a way to force the environment onto the national agenda. On September 20, 1969, in a talk at the University of Washington in Seattle, he announced plans for a nationwide “environmental teach-in” on college campuses.

Nelson made the effort bipartisan by recruiting Rep. Pete McCloskey, a conservation-minded California Republican, as co-chair. He then hired Denis Hayes, a young activist, to organize it. Hayes built a national staff of 85 people, and the event took the name Earth Day.

April 22, 1970

The first Earth Day fell on Wednesday, April 22, 1970. About 20 million Americans took part, around 10 percent of the population at the time, and more than 10,000 primary and secondary schools held activities that April. Americans demonstrated in cities across the country, and campuses held teach-ins on pollution.

The other Earth Day

A separate Earth Day came first by a month. In 1969 the peace activist John McConnell proposed a day honoring the Earth on the March equinox, and San Francisco Mayor Joseph Alioto proclaimed it on March 21, 1970. Some groups still observe that equinox version, but April 22 is the Earth Day most Americans know. For the astronomy behind the March date, see the guide to equinoxes and solstices.

What the First Earth Day Changed

The months after April 22, 1970, rebuilt federal environmental policy:

Date	Action
July 9, 1970	President Richard Nixon signs Reorganization Plan No. 3 to create the EPA
December 2, 1970	The Senate confirms William Ruckelshaus as the first EPA administrator, the agency’s traditional birthday
1970	Congress passes the Clean Air Act of 1970, setting national air quality standards and motor vehicle emission rules
1972	Major amendments to the 1948 Federal Water Pollution Control Act give the country the Clean Water Act
December 28, 1973	The Endangered Species Act is enacted

The EPA’s own history says Congress authorized the agency in response to the demonstrations, and EARTHDAY.ORG links the Clean Air Act and the agency’s creation directly to the first Earth Day.

When Is Earth Day? The April 22 Date Rule

The rule is simple: Earth Day is April 22 every year, and it has been since 1970. The weekday shifts forward one day each year, or two when a February 29 falls in between. Earth Day falls on a Thursday in 2027 and a Saturday in 2028, as the 2027 calendar shows.

April 22 was chosen for practical reasons. The organizers wanted college students, so they picked a weekday that fell after spring break and before final exams on most campuses. The date has never been moved to a Monday or tied to the equinox.

Because the date is fixed, Earth Day sometimes overlaps with moving religious holidays. It falls on the first day of Passover in 2027, as it did in 1997. In 2011 it fell on Good Friday. Many schools and communities stretch the observance into an Earth Week around April 22.

One coincidence still circulates: April 22, 1970, was the 100th anniversary of Vladimir Lenin’s birth on the Gregorian calendar. Nelson was reportedly unaware of it, and the date was chosen for the academic calendar, not for any anniversary.

How Earth Day Went Global

Earth Day stayed mostly American for its first two decades. That changed with the 20th anniversary:

• 1990: About 200 million people in 141 countries took part, turning Earth Day into an international event.
• 2000: Some 5,000 environmental groups reached people in a record 184 countries.
• 2009: The UN General Assembly adopted resolution 63/278, designating April 22 as International Mother Earth Day.
• 2010: The 40th anniversary drew an estimated 1 billion participants, according to organizers.
• 2016: Leaders from 175 nations signed the Paris climate agreement on Earth Day, April 22, 2016, a date you can find on the 2016 calendar.
• 2020: The 50th anniversary moved largely online because of the COVID-19 pandemic.

Earth Day and Other Environmental Dates

Earth Day is often confused with a few related observances, and the calendar helps keep them apart:

• International Mother Earth Day (April 22). The United Nations name for the same date, adopted in 2009.
• World Environment Day (June 5). A separate UN observance that grew out of the 1972 UN Conference on the Human Environment in Stockholm, the meeting that also created the UN Environment Programme.
• Equinox Earth Day (March 19-21). John McConnell’s version, tied to the March equinox, so its date shifts slightly from year to year.

The anniversaries make a neat pattern of their own. The 10th anniversary in 1980 centered on a main event in Washington, D.C., across from the White House. The 20th, in 1990, fell on a Sunday and became the first global Earth Day. The 50th, on April 22, 2020, fell on a Wednesday, the same weekday as the original in 1970, even though the events that year moved online.

How Americans Observe Earth Day

Most Earth Day activity is local and practical. Schools teach environmental lessons and run recycling drives. Volunteers clean up parks, rivers and beaches. Tree planting is a common Earth Day activity; in 1990 the EPA even announced a registry to record trees planted for Earth Day.

Federal agencies have used the date as well. EPA administrators have given Earth Day speeches and released environmental data around April 22 since the agency’s first years, including William Ruckelshaus’s remarks on April 22, 1971.

The tone of the day has shifted over five decades. The 1970 events were largely demonstrations and teach-ins; today Earth Day mixes advocacy with volunteering, school projects and corporate sustainability announcements. It arrives three weeks after April Fools’ Day and about two weeks before Cinco de Mayo, in the busy stretch of spring observances.