Las Vegas is a city in the Nevada desert. Randall Flagg gathered his followers there.
Rioting, looting and vigilantism swept Las Vegas as the superflu's uncontrollable outbreak led to the total collapse of civilization. After a few weeks, almost everyone in the city was dead. Randall Flagg, "the Dark Man" or "the Walkin' Dude," appeared there and began summoning followers to him. People attracted to power, or to law and order (even at a steep price), were common among those who answered Flagg's call.
The city was eventually cleaned up and electrical power was restored. Randall Flagg created a strict code of laws to govern Law Vegas, which included such items as a total ban on all recreational drugs. The punishment for drug use was death by crucifixion. Nearly all crimes under Flagg's code of law were punished by crucifixion or execution.
Las Vegas remained Flagg's center of power as his followers began searching the surrounding wasteland. They found operable jet aircraft and helicopters at Nellis Air Force Base, and with a surviving civilian pilot or two among them, they began training to use them. Work crews and salvage teams continued carrying out repair and cleanup efforts, and enough children were gathered among the survivors that Vegas began to hold school classes again.
The speedy restoration of order and some of the comforts of civilization came at a steep price. In addition to a draconian system of law, the inhabitants of Las Vegas were subject to Flagg's will in every sense of the word. Flagg's all-seeing Eye allowed him to literally sense treason, doubt, hesitation and disloyalty among his subjects, and his henchmen dealt with all such elements swiftly and harshly.
Despite his ever-tightening iron grip, Flagg's control began to falter. He began making mistakes, and people began to slip away in the night in increasing numbers as a sense that something ominous was coming developed among Flagg's followers. That something arrived in the form of the Trashcan Man, who retrieved a nuclear warhead from Nellis Air Force Base following his sabotage of the helicopters, which killed all of the flight instructors and most of the trainee crews. Trashcan Man intended to offer the warhead's power as a gift, an offering in apology for his misdeeds to Flagg.
As the Hand of God descended from the sky and armed the warhead, Flagg abandoned his human form and vanished. The nuclear warhead then exploded: "and righteous and unrighteous alike were consumed in that unholy fire."
Las Vegas was completely destroyed in the explosion.