The number of trafficking victims in the United States is not known, but advocate groups estimate the total number reaches into the hundreds of thousands.
Advocates say there are warning signs to help identify victims of sex trafficking.
Authorities say the cycle of sex trafficking is difficult to break.
This map shows potential trafficking cases from 2015 tracked by Polaris and the National Human Trafficking Resource Center. This is not intended to represent the entire scope of the trafficking problem, but to show trends.
RESOURCES TO HELP
Salvation Army STOP-IT Hotline: 1-877-606-3158
National Human Trafficking Hotline: 1-888-373-7888
Cook County Human Trafficking Task Force
Salt & Light Coalition