Where a report usually goes
Where a person appears to be in danger right now, the call goes to 911. Otherwise, a report can go to the local police precinct or, where you suspect someone is being controlled or forced, to the National Human Trafficking Hotline, which can connect a case with local services and law enforcement. Anonymous tips are often accepted, although a way to follow up can help investigators. Building owners and managers sometimes have their own reasons to act, since premises used this way can become the subject of civil proceedings against the property. A report is not an accusation you have to prove; investigators decide what, if anything, follows.
Useful details and real risks
Dates, times, addresses, vehicle descriptions, and any online ads you saw are the kind of details that help. Do not try to investigate on your own: following people, photographing them up close, entering a unit, or confronting anyone can put you and others at risk, and it can interfere with a real investigation. If you think someone is being exploited, keep in mind that they may be the person most in need of protection rather than punishment. Stick to what you actually observed when you make the report, and leave out speculation about who is involved or why.
When a lawyer should be involved
Some people looking up how to make a report are caught up in the situation themselves: an employee at a business where it happens, a landlord who has received a complaint, or a person who was once involved and wants out. In those cases it helps to speak with a lawyer before or alongside a report, so you understand your own position. Survivors of trafficking may have protections, including immigration relief for some and, in New York, a way to ask a court to vacate certain past convictions. In a first conversation we go through what you know, what worries you, and how a report could affect you.