Earth Hour 2009

Earth Hour 2010 was reportedly the biggest Earth Hour yet, aiming to garner more than the one billion participant goal of 2009's Earth Hour.
126 countries participated in Earth Hour 2010.
In the United States polling shows that an estimated 90,000,000 Americans participated in Earth Hour as lights were turned off around the country, including iconic landmarks such as Mount Rushmore, the Las Vegas Strip, the Empire State Building and Niagara Falls.
Earth Hour will be carried out in practical ways, as cities and landmarks apply the core principle of turning off the lights to their everyday routine. In Chicago, the Building Owners and Managers Association (BOMA) developed lighting guidelines to reduce light pollution, and reduce the carbon footprint of downtown buildings. Mount Rushmore in South Dakota will now start powering down each night around 9 p.m. instead of 11 p.m.