Until now there hasn't been a lot of data to help law enforcement and policymakers better understand the economics of the illegal sex trade and trafficking.
But a study released Wednesday by the Urban Institute's Justice Policy Center analyzes the size and structure of the underground commercial sex economies in eight major cities: San Diego, Seattle, Dallas, Denver, Washington, D.C., Miami, Atlanta and Kansas City, Missouri.
The three-year effort, which began in 2010, was funded by a $500,000 grant from the U.S. Department of Justice, which supports research that can aid in the prevention, detection and prosecution of human trafficking.
Researchers interviewed pimps, traffickers, sex workers and child pornography offenders, as well as local and federal law enforcement officers.
Of the eight cities studied, Atlanta had the largest cash-based underground sex economy at $290 million a year and Denver the smallest at $40 million, based on 2007 data. (There was insufficient data available for Kansas City, so it was dropped from the estimation analysis.