State of Sex was a dissertation written by a couple of scholars at UNLV (the University of Nevada, Las Vegas) about the history of prostitution in Nevada. I came across this book in my research and couldn't put it down.
The State of Sex: Tourism, Sex and Sin in the New American Heartland
By Barbara G. Brents, Crystal A. Jackson, Kathryn
This book is almost like the book version of the movie, except that it only covers the brothels. The women journey to the brothels and wrote a book about it and juxtaposed the legalized version of against the commerce of sex in America.