The First Widespread Earth Day Celebration
The Earth Day most often celebrated in the United States—and in many other countries around the world—first took place on April 22, 1970. It was a nationwide teach-in about the environment, dreamed up by U.S. Sen. Gaylord Nelson (a Democrat from Wisconsin) and modeled on the anti-war teach-in demonstrations that Vietnam war protesters had used successfully to educate people about their issues.
More than 20 million people turned out at thousands of colleges, universities and communities all across America for that first Earth Day, which sparked a global environmental reawakening. More than half a billion people in 175 countries now celebrate Earth Day on April 22.
A Second Claim to "First Earth Day"
Yet, it may surprise you to learn that April 22, 1970 was not the first Earth Day. A month earlier, San Francisco Mayor Joseph Alioto had issued the first-ever Earth Day proclamation on March 21, 1970.
Mayor Alioto's action was inspired by John McConnell, a San Francisco publisher and peace activist, who a year earlier had attended the 1969 UNESCO Conference on the Environment where he proposed an international holiday focused on environmental stewardship and preservation. McConnell suggested that Earth Day coincide with the March equinox—the first day of spring in the northern hemisphere, the first day of autumn south of the equator—which always falls on either March 20 or March 21.
About a year later, on February 26, 1971, then-UN Secretary General U Thant supported McConnell's proposal for an annual global Earth Day celebration at the March equinox, and issued a proclamation to make it official.