Casino lights along the Las Vegas Strip are going dark as part of a worldwide effort to bring attention to climate change.
The Saturday event, organized by World Wildlife Fund, involves more than 3,500 cities in 125 countries. Officials say all 50 states in the United States are taking part.
In Sin City, nonessential lighting will go off at 8:30 p.m. for one hour.
That will include the "Welcome to Fabulous Las Vegas, Nevada" sign.
Several casinos in downtown Reno are also participating.