(Covers information from Anderson's universe)
Las Vegas was an American city located in the state of Nevada, known as "Sin City" for it's variety of entertainments.
During the global outbreak of the t-virus, the city was overwhelmed; after five years the city once again became a desert wasteland. By the time the convoy lead by Claire Redfield reached the city to search for supplies, it was devoid of undead, picked clean by crows.
It was here that Dr. Sam Isaacs of the Umbrella Corporation set a trap for Alice using his Super Undead. Alice, Claire and the members of her convoy fought the Super Undead while Isaacs monitored the activity in a Umbrella tent on a rooftop. Issacs escaped after being bitten by a Super Undead and though the survivors emerged victorious against the undead, most of the convoy was wiped out during the battle.