By the late 1960s, many Americans were getting fed up with bad news about the environment. A book early in the decade warned about the dangers of pesticides. An oil spill on the coast of California killed thousands of birds and other creatures. A river in Ohio caught fire. And pictures snapped by an Apollo astronaut showed Earth as a fragile blue ball.
To inform Americans about the problems, Senator Gaylord Nelson of Wisconsin organized an “environmental sit-in.” It was held on April 22nd, 1970 — the first Earth Day. And an estimated 20 million people took part.