If nuclear war ever breaks out, here's a suggestion on where to take cover. North of Yellowstone in a place called Paradise Valley there's a remarkable number of places to hide underground.
We visited two amazing underground structures in Paradise Valley. Each could hold a substantial community for the better part of a year. But we just barely scratched below the surface. In all there are about 30 big shelters, a hedge against "Doomsday in Paradise."
In the splendid scenery of Paradise Valley, you might overlook the clues: ventilation equipment, vault-like doors in hillsides, a watchtower that could double as a machine-gun nest.
If you're lucky, you can take a special tour with Phillip Hoag who designed a shelter called Mark's Ark, a sort of Motel 6, 20 feet under.
Phillip Hoag: "In fact people have asked me, 'Why don't you live down here?' I say, 'Are you nuts?' you know, the only reason I'd come down here would be because I had to."
The first 90 feet of walking gets you through the entryway. It's cluttered with spare parts that might be useful in a long-term disaster. There's a decontamination room and an engine room, with three diesel engines with enough fuel to power a community for a long time.
The main shelter is 32 feet across, 132 feet long. It has three floors and 40 bedrooms! They're individually furnished by families that will live in them someday, if things get really bad outside.
There's even an auxiliary shelter for pets. The long corridors are packed with dehydrated food, lentils, beans and oatmeal. There's a well-stocked clinic and a big community kitchen.
Phillip Hoag: "Easily feed a hundred and fifty."
But why would 150 people want to go underground for a year? Neighbors contributed $6,000 a person to build the shelter 15 years ago, worried about nuclear war.
Phillip Hoag: "I think the threat is greater today than it was 15 years ago."
About a mile away, Charlie Hull showed us his community shelter, Liberty Lighthouse. Although it's 300 feet long, it's cozier than Mark's Ark, designed for fewer people.
Charlie Hull: "We got plenty of toilets for a population of, we figure, about 90 people."
This one is painted and decorated as if someone really intends to live here. It has a spacious living room and well-appointed bedrooms.
In all, there are about 30 community shelters in the area. It started in the 1980's with predictions of nuclear war by a controversial local religious group, the Church Universal and Triumphant. The shelter craze spread to the church's neighbors.
Hull thinks the nuclear threat has evaporated, but he's still worried about a natural catastrophe involving extreme wind, when the Earth tips on its axis.
Charlie Hull: "Now if that happens, it throws the whole kilter of the air cycles off. The jet stream, instead of staying up there, could come right down on the surface and, man, 300 mile-an-hour winds would just change your life entirely."
Many original participants dropped out over the years, stopped paying small monthly maintenance fees, no longer hedging bets against catastrophe. Phillip Hoag: "So, if anything happens, whoever's around and would like to use it, we'll make it available to them. Hah, hah, hah, but, of course it hasn't happened. Makes us look a little foolish. But, uh, I'm not ashamed of it at all."
In Paradise Valley they think the rest of America is woefully under-prepared. And when the time comes, they may not have the last laugh, but they may just have the last good place to go.