More about slavery...

According to the United States State Department, potentially 4 million people were sold into slavery and trafficked and held against their will in 2001. The State Department determined that slave holders and traffickers usually use threats and intimidation to hold people. According to the report, women and children make up the majority of modern day slaves. 50,000 women and children are trafficked annually for sex exploitation into the United States. Victims typically find themselves isolated once they are transported into a new country because they usually cannot speak the language. Trafficking of people usually happens in countries where the economies are unstable as are their governments because usually promises for better pay looks a lot better than the conditions that most people are living in. Trafficking acts that combat trafficking of persons have been put in place, but most people in slavery are hard to find because they won't talk, and the laws just aren't enforced well.

http://usgovinfo.about.com/library/weekly/aa061202a.htm