why is earth day on april 22

Earth Day is celebrated on April 22 because that date was chosen by U.S. Senator Gaylord Nelson in 1970 to maximize participation on college campuses for what he conceived as an "environmental teach-in." The week of April 19–25 was selected as it did not conflict with exams, spring breaks, or major religious holidays like Easter or Passover, and the weather was typically decent for outdoor activities. April 22 was specifically picked because it was a Wednesday during that week, making it an ideal day for students and others to engage in environmental activism. This date also falls shortly after the birthday of conservationist John Muir. The first Earth Day on April 22, 1970, saw about 20 million Americans participate in rallies and events, making it a pivotal moment that helped launch the modern environmental movement and led to the establishment of the Environmental Protection Agency (EPA) in the United States. The choice of the date was practical and strategic rather than symbolic, though it coincidentally was also the 100th anniversary of Vladimir Lenin's birth according to the Gregorian calendar, which some skeptics pointed to as a political conspiracy without evidence. In summary, Earth Day is on April 22 because it was the most advantageous timing for college and community involvement when the first nationwide environmental demonstration was organized in 1970 by Senator Nelson and others to raise public awareness and action on environmental issues.