Now, for the first time, a state study estimates that at least 1,000 children -- some as young as 12 -- work as slaves in Ohio each year.
More than 800 people from foreign countries are also being forced into brothels, farms or factories. The number of modern day slaves is much higher, according to the study commissioned by Attorney General Richard Cordray.
That's because it could not estimate the number of adult Americans who are being forced to work in the state. It's a difficult crime to combat.
Human traffickers regularly move victims around the country to decrease the chance that the victim will learn their whereabouts or build a relationship with someone who will help them escape.
Victims also are often afraid of police, or they are warned they'll be beaten or killed if they cooperate.
Cordray said Northeast Ohio is an attractive area for human traffickers to bring victims because of its large population and its vicinity to major roadways.
The study found many police officers unaware of the problem and how to identify it, and that prosecutors rarely go after traffickers by leveling severe charges.
Channel 3 News went undercover with the Cuyahoga County Sheriff's officers try to uncover evidence of human trafficking.
For three days in December, cameras followed detectives as they surfed Internet sites, setting up "dates" at a local hotel. More often than not, they found women selling sex, but no evidence of human trafficking.
Undercover stings like this are happening around Ohio, with authorities hoping to rescue girls and women from the sex trade and prosecute those who forced them to sell their bodies.
The study found it's a growing problem in Ohio, particularly related to the sex trade. The reason is simple: An insatiable appetite for sexual services.
Ohio ranks 5th nationally for the number of strip clubs it has. It's a seller's market, and human traffickers are filling the void.
"Many of our youth are at risk," said Cordray. "We estimate that one in three youths who is away from home for two weeks will end up trafficked for sex."
The study says children are at particular risk of being forced into the sex trade in Ohio because of law enforcement's weak response to human trafficking.
It also said children from Ohio are more likely to be sent elsewhere than put to work here.
Meanwhile, many victims, especially those from eastern Europe, are being flown to Toronto and smuggled across the border in Michigan before ending up in Ohio.
The study said foreign-born victims are also likely to be sent here from Chicago and Detroit.