Harold Camping, 89, previously made a failed prediction that Jesus Christ would return to Earth in 1994.
But the head of the Christian radio network Family Stations Inc says he is sure an earthquake will shake the Earth on May 21, sweeping true believers to heaven and leaving others behind to be engulfed in the world's destruction over a few months.
"We know without any shadow of a doubt it is going to happen," said Camping, whose Family Radio broadcasts in more than 30 languages and on U.S. and international stations.
His supporters have posted about 2,200 billboards around the United States about the coming apocalypse, and dozens of followers are driving across the country to spread the news.
Volunteers also handed out pamphlets warning about May 21 as far away as the Philippines, telling people God had left clear signs the world was coming to an end.
Camping, a civil engineer who ran his own construction business before turning to evangelism, told Reuters he planned to spend May 21 with his wife and watch the doomsday unfold.
"I'll probably try to be very near a TV or a radio or something," he said. "I'll be interested in what's happening on the other side of the world as this begins."
Like his last prediction, Camping's doomsday date is based on his reading of the Bible and a timeline dating back to ancient events including the Biblical flood survived by Noah.
Camping's pronouncement of a specific date for the apocalypse puts him outside the Christian mainstream.
But his contention that the souls of believers will leave their bodies and enter heaven in a rapture is a central tenet within many Christian churches.
Stephen O'Leary, an expert in religious communication at the University of Southern California, said the idea of rapture first appeared in Christian teaching in the 19th century.
"It is very appealing to people," said Barbara Rossing, professor of the New Testament at the Lutheran School of Theology at Chicago who describes "an enormous end-times prophecy industry" including video games, board games, books and more.
Tom Evans, a spokesman for Camping, said at least several tens of thousands of people listen to Family Radio's message.
One of those is Allison Warden, 29, of Raleigh, North Carolina, who most recently worked as a payroll clerk for an Ohio company and now runs the end-times website Wecanknow.com.
"My boss does not agree with this but has been very understanding and supportive," she said. "He thinks next week I'll be back to work like normal."
