Much of Las Vegas plunged into darkness Saturday night for one hour as the city known for its lights took part in Earth Hour.
Everyone was asked to turn off outdoor lights and any inside lights that weren't being used between 8:30 p.m. and 9:30 p.m. Even the famous Welcome to Fabulous Las Vegas sign even went dark.
Many of the casino properties, on and off the Las Vegas Strip, took part in the event.
"The specific actions that we are calling for is from the national level to address climate change as well as the international level," said Nick Sundte with the World Wildlife Fund.
Officials hope that turning off the lights will help raise awareness about global warming and climate change.
Earth Hour was a worldwide energy conserving campaign. Nearly 4,000 cities and towns in 88 countries took part in the event. In Sydney, Australia, the lights were turned off at the famed Opera House.
China also took part in the campaign for the first time. Officials there turned off the lights at Beijing's Bird's Nest Stadium and Water Cube which were prominent venues for the 2008 Olympics.