In what year was the first Earth Day celebrated?

By the 60s, many people were already becoming aware of the effect of pollution on our environment. And in 1969, Senator Gaylord Nelson developed the idea of Earth Day, after being inspired by Anti-Vietnam protests. He thought that if we can protest against war, then we can surely protest against the destruction of our environment. So on April 22, 1970, the first Earth Day happened, with multiple protests happening simultaneously in cities across the Nation. It is still celebrated on the same date every year, and is one of the important avenues for confronting the current climate crisis.