By Pascal Barollier
Washington - It is called a vacation "au naturel", using a French expression as a fig leaf to cover up its more common name of naturism.
The United States is a deeply conservative country and some inhibitions take time to cast off, but Americans are starting to flock to beaches and country parks reserved for nudists, especially at the luxury end of the market.
"People are looking for a more relaxed way to spend their vacation," according to Carolyn Hawkins, public relations coordinator for the American Association for Nude Recreation (AANR).
"They find visiting a nudist resort, they can travel more and pack less."
The AANR estimates that naturist clubs and beaches for those who soak up the sun "au naturel" earn about $500-million a year now, against $200-million in 1992.
"The interest has been increasing over the last 10 years," said Carrie Schultz, marketing director for the Caliente Resort, an upmarket nudist colony near Tampa in southern Florida, which has about 300 apartments, bungalows and houses that cost between $200 000 and $500 000.
"People who bought here used to go to the Caribbean to find nude facilities. Upscale nude resorts didn't exist in the US," said Shultz.
"Shields are coming off. We are not afraid to run TV commercials and people know it is here. Caliente is family oriented, with a children's playground and events for kids. In terms of luxury accommodations, we are off the scale."
Caliente highlights how naturism in the United States has become more sophisticated to reach its market.
Specialist agencies, such as Bare Necessities, based in Austin, Texas, offer cruises to the Caribbean and Europe, buying up whole ships and then selling holidays for between $800 and $5 000 per person.
"Nude recreation has grown so much in the US because there are more upscale availabilities, more than going to a camp site," said Nancy Tiemann, who started Bare Necessities in the early 1990s.
"Americans are a little spoiled. They want something with more amenities. When we started our business, major cruise lines would not respond, it was difficult to find somebody who would take my call.
"Then they started to take a look at us. When that kind of money is being spent, people take notice."
The AANR has listed 270 naturist organisations in the United States, including 18 created in the past year.
On its map of "au naturel" beaches are a large number in Florida, with its year-round sunshine. Haulover, near Miami, and Apollo Beach, near the Kennedy Space Center, are among the best known.
"Very few beaches are legal for nude recreation in the US. Nude recreation is not for everybody, but it is important that people have the choice," said Hawkins.
Where they do, beach-goers are warned by signs which say: "You may encounter nudity beyond this point."
The AANR is trying to persuade the national park service to give more space to naturists. It has particularly targeted the island of Assateague off the east coast of Maryland state.
It carried out a survey of people in the locality, 50 percent of whom said they would welcome naturists, as long as the warning signs were put up for others.
But the AANR is also aware how conservative the United States is.
It paid for another, national survey which that only 14 percent of Americans gave strong support for things "au naturel".