The Howard Hughes Corp. will turn off all the lights to Summerlin's main entry monument on Summerlin Parkway during Earth Hour, 8:30 to 9:30 p.m. Saturday, and urges residents to participate. The monument is just west of the Rampart Boulevard interchange.

"Summerlin is the first master-planned community in Las Vegas to sign up to participate in Earth Hour," said Tom Warden, senior vice president of community and government relations for The Howard Hughes Corp., developer of Summerlin.