When the BBC commissioned documentary film maker Jane Hilton to make “Love for Sale” 13 years ago, the 10-part series on Nevada’s legalised prostitution lifted the veil on the world's oldest profession.
Since then, Hilton's interest in this project has remained high, and in 2010 she decided to return, with her plate camera, to create intimate nude portraits of these girls.
She told HuffPost UK Lifestyle: "Returning back into the brothels was just as interesting this time as it ever has, it is just such a fascinating subject because every woman who works there has an interesting story.
No matter what you have heard before, you will hear something equally astounding from the next person.
"Going back 10 years later I found that the industry had moved on, in a way that the women were not so frightened if other people found out what they did. This has to be down to the internet, and the fact that maybe it has moved in a very small amount in becoming more socially acceptable; although that still has a long way to go."
Hilton visited 11 brothels, including Madam Kitty’s Cathouse and Moonlite Bunny Ranch, and an exhibition of photographs is now running at the Nailya Alexander Gallery in New York until July 13.
In a recent blog for the HuffPost UK, the London-based photographer describes how these women see themselves as 'carers', as much as sex workers, saying that just 30% or 40% of their time is spent participating in sexual activity.
HIlton told HuffPost UK Lifestyle: "I have always been non judgmental about what these women do for a living. What frustrates me the most is ignorance.
"Of course prostitution is different in every culture, and prostitution I have photographed is very different to some of the hideous scenarios around the globe.
"In Nevada it is legal, the girls pay their taxes, they work in safe houses and are tested every week."
Warning: This slideshow contains images of a sexually explicit nature