State Department's 'Trafficking in Persons' Report: Scope, Aid Restrictions, and Methodology [Updated October 30, 2019] [open pdf - 2MB]
From the Introduction: "The State Department estimates that globally there are 24.9 million victims of human trafficking, also commonly referred to as modern slavery. Several international mechanisms exist to define and address human trafficking, such as the Protocol to Prevent, Suppress and Punish Trafficking in Persons (the Palermo Protocol) and the United Nations (U.N.) Convention against Transnational Organized Crime. In the United States, Congress has led efforts to eliminate severe forms of trafficking in persons domestically and internationally, particularly with its enactment of the Victims of Trafficking and Violence Protection Act of 2000 (P.L. 106-386). Division A of that act, the Trafficking Victims Protection Act of 2000 (TVPA), established U.S. antitrafficking policy to (1) 'prevent' trafficking, (2) 'protect' trafficking victims, and (3) 'prosecute' and punish traffickers (known as the three Ps)."
CRS Report for Congress, R44953
Congressional Research Service: https://crsreports.congress.gov/