Earth Day has been celebrated every April 22 since 1970. Some 20 million people marked the first one and a lot has been done to protect the environment since then. The ozone layer may still be a burning issue but both air and water quality are much improved. Recycling has become a way of life -- and a daily chore -- for millions of people. And the green movement is now part of the social fabric as well as the business community.
Throughout the U.S., there are hundreds of federal, state and local events marking the day, but Earth Day is definitely a global event. Here's a sampling of our coverage.