On April 22, 1970, the very first Earth Day, more than 20 million people joined in demonstrations across the United States.
Colleges organized teach-ins to draw attention to the pressing environmental issues of air and water pollution. A part of New York City's Fifth Avenue was shut down to accommodate the marching crowds. Congress recessed so that members could join the days' activities.
Organizers said it was the largest national protest in U.S. history.
Today, Earth Day participants are...Full Story