President Obama declared January "Human Trafficking Prevention Month." Human trafficking, the modern version of slavery, might seem like one of those things that only happens overseas in desperate, lawless places where people cannot protect themselves.

Sadly, this isn't the case. Instead, human trafficking is the fastest growing illegal activity in the U.S. Across the country men, women and children are trapped in involuntary servitude. Sometimes the victims are runaways, but more typically they are foreigners desperate for a better life. They are lured here with the promise of a decent job or an education. What they find when they arrive is something totally different: they are forced to work brutally long hours, perform menial or backbreaking labor or prostitute themselves for someone's else's profit.

Just last month police in Newark, New Jersey, arrested a woman for trafficking in young. African women and girls Promising her victims a U.S. education, the trafficker brought girls as young as 10 from Ghana into the country and then forced them to work in her salon braiding hair from early morning until late at night six or seven days a week. Thankfully, someone finally recognized that these girls were the modern day slaves and alerted authorities.

Unfortunately, stories like this abound. Human trafficking affects millions of people around the world. In its most recent annual report on this issue, the State Department says that over 12 million people live in some form of bondage. The majority are women and children.

According to the International Labor Organization, the vast majority of people who are trafficked are like the young girls from Ghana; they are illegally forced to work under abusive conditions, some as domestic servants, others in fields as agricultural laborers, still others in factories. Some are sexually trafficked and some are taken to pay off family debts with their labor. All suffer in countless ways.

This illegal activity exists because some people benefit from the abuse of others. Not only do victims provide cheap labor, trade in their labor generates revenue that traffickers use for a variety of purposes: to purchase arms, to buy supplies for rebel groups or to support activities in the drug trade. The State Department report says that in 2010 this illegal trade was worth over $32 billion.

What can be done to prevent these kinds of terrible abuses? A first step in some countries would be to enforce legislation that criminalizes human trafficking. In 2003 a United Nations Protocol outlawing human trafficking came into effect. Over 170 countries have signed this protocol but this has not necessarily translated into meaningful protection for people. In too many countries governments are unable or unwilling to enforce anti-trafficking laws and prosecute offenders

Ultimately, however, human trafficking is an economic issue. Expanding economic opportunity for people around the world will help relieve the financial and family pressures that lead many, against their will, into servitude.

On this front, vastly more can be done to promote job growth, reduce corruption and improve local economies. Governments can continue the work of improving the local climate for doing business. Government officials can make it easier for entrepreneurs to open and effectively run businesses. They can enact policies that encourage trade and reduce regulatory barriers that make trade costly. Providing people with more economic opportunity should make it harder for human traffickers to victimize the poor and the vulnerable.

Prosecuting wrongdoers is surely an important component of the fight against human trafficking. But prosecutions alone won't solve this problem. Abolishing modern slavery will require economic emancipation.

Karol C. Boudreaux is a senior research fellow at the Mercatus Center at George Mason University and lead researcher for Enterprise Africa!, an international initiative to promote successful business development in Africa. She is an internationally recognized expert on the role played by private institutions to alleviate poverty and promote prosperity.