Either people leave the country to to it or women and kids are imported and enslaved.
Experts: Vt. Sex Slavery Fits U.S. PatternJuly 23, 2004
http://www.timesleader.com/mld/timesleader/9223928.htm The regulars at the Park Place Tavern weren't surprised when police raided what is being described as an Asian brothel in a small house across their shared driveway. But they were surprised when news reports linked the now-closed Tokyo Spa and two other health clubs in the area to what police say is an international prostitution ring that smuggled Asian women into the United States and made them sex slaves.
"We joked about it here all the time," said Sandy Maloney, who lives in an apartment complex out back.
Maloney said she watched as older men driving expensive out-of-state sport utility vehicles visited the Tokyo Spa at all hours.
SNIP
"Modern-day slavery is the fastest growing criminal industry in the world," said Derek Ellerman, co-executive director of the Washington-based Polaris Project, a grass-roots anti-trafficking organization.
Sex slavery: The growing tradeMarch 8, 2001
http://archives.cnn.com/2001/WORLD/europe/03/08/women.t... /
Up to 120,000 women are smuggled into western Europe, mainly from central and eastern Europe, and forced into prostitution.
A report by the Protection Project, based at Johns Hopkins University, in Baltimore, Maryland, has documented the rising trends in the sex slave trade.
It says more than 15,000 women are trafficked into the United States every year, many of them young girls from Mexico.
The project also claims that Asian women are sold to brothels in North America for $16,000 each.
I can't find it right now but last year there was an article on how even the Netherlands has this problem with slavery. Legalizing prostitution does not prevent this from happening.