On Tuesday, Boston launched an education campaign to mark the observance of National Human Trafficking Awareness Day.
As the campaign begins, city officials acknowledge they don't know the full extent of prostitution, but believe it involves hundreds of children and adults.
City health officials, police and the district attorney say the crime is largely invisible because it's covert and the victims don't report it to police.
In 2009, Boston police investigated 220 reports of what Suffolk County District Attorney Dan Conley calls sexual exploitation by pimps and johns.
The campaign is called End Demand One By One.
This program aired on January 11, 2011. The audio for this program is not available.