Attorney General's Annual Report to Congress and Assessment of U.S. Government Activities to Combat Trafficking in Persons: Fiscal Year 2013 [open pdf - 3MB]
From the Introduction: "Traffickers target all populations, around the world and right next door: women and men, adults and children, citizens and non-citizens, English speakers and non-English speakers, and people from all socioeconomic groups. Some populations--such as runaway children, undocumented immigrants, indigent people, and individuals with physical and mental disabilities--are particularly vulnerable to trafficking. Victims are often lured by traffickers with false promises of good jobs and better lives, and then forced to work under brutal and inhumane conditions. Due to the hidden nature of the crime--human trafficking victims may work in the open, but the coercion that ensnares them may be more subtle--it is difficult to accurately estimate the number of victims. Despite this challenge, the United States has led the world in the campaign against this terrible crime both at home and overseas."
U.S. Department of Justice: http://www.justice.gov/