Earth Day was first celebrated on April 22, 1970, and has been growing strong ever since. Here's a look back at our Earth Day roots, with updates of the latest numbers.

20 million: Number of people who celebrated the first Earth Day

200 million: Number of people who celebrated Earth Day in 1990

500 million: Number of people who celebrated Earth Day in 2000

175: Number of countries worldwide that celebrate a designated Earth Day 

3.7 billion: World population in 1970

6.7 billion: World population in 2009

65.2 million: Number of Google hits for "Earth Day"

146 million: Number of Google hits for "Green Day"

111.2 million: Number of vehicles on the road in the United States in 1970

238.3 million: Number of vehicles on the road in the United States in 2009

20: Number of cars needed to emit the same amount of greenhouse gas emissions as one pre-1970 model

57.2°: Average global temperature from 1970-1979 (in degrees Fahrenheit)

58.3°: Average global temperature from 2000-2008 (in degrees Fahrenheit)

220,000: Tons of U.S. lead emissions in 1970

4,000: Tons of U.S. lead emissions in 2008

75: Percent increase in greenhouse gas emissions from 1970 to 2004

100 million: Number of plastic bags thrown away annually in the United States

0: Number of plastic bags available at Whole Foods as of Earth Day 2008

150 million: Estimated number of plastic bags that have been kept out of landfills since Earth Day 2008

This article originally appeared in Plenty in April 2008.

Copyright Environ Press 2008

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