<p>A main avenue is empty of private cars on A Day Without Cars seen from a bridge decorated with a statue of a pedestrian in Medellin, Colombia, Thursday, April 22, 2010. The Day Without Cars marks the 40th anniversary of Earth Day. (AP Photo/Luis Benavides)</p>
April 23, 2010
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April 23, 2010 9 p.m.
Earth Day evolves
WASHINGTON - There was no "Green Movement" yet and little talk of global warming. Instead, the original Earth Day 40 years ago emphasized "ecology" and goals like cleaning up pollution and litter - along with a more anti-establishment vibe than today.