We call them caravans. Americans call them trailers. Hollywood's elite have started calling them home, says Gary Andrew Poole
Hollywood has a weird way of redefining low-brow habits and turning them into hip trends. For example, studio executives like to drive 4-wheel trucks - on their daily commute on smooth Los Angeles freeways. Or they wear cowboy boots and baseball caps to important meetings. Or down-dating as in Julia Roberts/Lyle Lovett or Claudia Schiffer/David Copperfield. But now comes one of the oddest "down-living" trends.

Within the last few years, movie stars have started buying trailers. That's right: smallish metal objects that are towed behind trucks. Trailers. Often they live in them while shooting a movie. That's the case with Tom Hanks, Tim Burton and Andy Garcia. After the Malibu fire, Sean Penn started living in his all of the time.

This being Hollywood, a certain kind of trailer has become the one to have, and it's called an Airstream. These aluminum-skinned mobile homes cost about $60,000 for a 34-footer, $25,000 for a 21-footer. But stars don't want a trailer made for a normal person, they want a luxury mobile. With that in mind, Neiman Marcus, the Dallas-based "billionaire's department store", is selling a custom designed trailer that has "ceilings resembling a blue sky with clouds; walls are painted with romantic outdoor scenes; doorways have hanging beadwork; tables feature a marquetry design". In America, Airstreams are usually found in ratty trailer parks or retirement villages. The Neiman Marcus-designed trailer costs $195,000.

Which has made Airstreams into offbeat objets d'art. Hollywood types now have their assistants scouting for vintage Airstreams that they can buy from an unsuspecting, retired old person for $10,000 or less. The actor Matthew Modine has three Airstreams, one of which looks like a submarine inside, complete with a 50lb metal bathroom door studded with rivets.

Maybe it's California's many natural disasters - earthquakes, wildfires, and mudslides - that make stars show more than a passing interest in a mobile home. But there are benefits. Stars are on location constantly and want a comfortable place to stay. Plus, they want something cool. Thus, as Barbara Jakobsen of New York's Museum of Modern Art said: "For people who prize American industrial design, Airstream ... is one of the primary objects of this century!"

Like migrating birds, older Americans like to go south for the winter to retirement trailer parks in warmer climates such as Arizona and Florida. These polyester-wearing grey-hairs often live in silver bullet-design Airstream trailers, which can sleep two comfortably.

"I had a 34-footer," says Ron Reid, a retiree from Desert Center, California. He recently sold his Airstream for $40,000 because the market seemed to be picking up and because he wanted a smaller trailer. He practically cries when he thinks about his Airstream. He says he misses it because it was "quality-built" and had "no resistance" when he took it on long highway trips. When Mr Reid was told that Hollywood stars are now becoming "Streamers", he cursed himself ("Rats!") for not trying to sell to Tom Cruise.

The Airstream got its start in the Thirties. Wally Byam, who invented the Airstream, was a merchant seaman for three years before returning to the United States to earn a law degree from Stanford. He was editing a do-it-yourself magazine in 1931 when he ran plans for a build-it-yourself trailer. His readers said it didn't work. They were right. So Byam worked on improved prototypes until 1934 when he rolled out his first trailer. It looked like a sausage on wheels. It would, he declared, travel down the road "like a stream of air". At first, Byam was making wood-panelled trailers, then, in 1937, he made an aluminum trailer called a Clipper. To date, 74,000 Airstreams have been sold, says John Beaver, Airstream's director of marketing.

The chances of seeing Sean Penn and other movie stars at the annual international rally that culminates on Wally Byam's fourth of July birthday - where members wear navy-blue berets and have special identification numbers - are remote, but the trend is still a hot one.

Hence, MTV's West Coast headquarters is featuring a '57 Airstream as a waiting room. And the Hollywood Canteen has an Airstream on its patio. The Canteen is supposedly one of the best star-gazing restaurants in Hollywood with regular Jack Nicholson, Johnny Depp, and Drew Barrymore sightings, who are there, perhaps, to gaze at the vintage Airstream.