From the introduction to the CRS report, Anti-Money Laundering: An Overview for Congress (Mar. 1, 2017 R44776):
Anti-money laundering (AML) refers to efforts to prevent criminal exploitation of financial systems to conceal the location, ownership, source, nature, or control of illicit proceeds. Despite the existence of long-standing domestic regulatory and enforcement mechanisms, as well as international commitments and guidance on best practices, policymakers remain challenged to identify and address policy gaps and new laundering methods that criminals exploit. According to United Nations estimates recognized by the U.S. Department of the Treasury, criminals in the United States generate some $300 billion in illicit proceeds that might involve money laundering. Rough International Monetary Fund estimates also indicate that the global volume of money laundering could amount to as much as 2.7% of the world’s gross domestic product, or $1.6 trillion annually.
For much more, see Money Laundering: An Overview of 18 U.S.C. § 1956 and Related Federal Criminal Law (Nov. 30, 3017 RL33315). — Joe