In late January, a statewide task force made hundreds of arrests in conjunction with National Human Trafficking Prevention Month. Sustaining such efforts throughout the year requires understanding the scope of human trafficking and how to combat it. The available data suggest that California accounts for a shrinking share of the trafficking incidents that occur nationally. However, detecting human trafficking is challenging—and the state can do more to contribute to national efforts to gather and disseminate information aimed at helping trafficked people and punishing those who traffic them.

Human trafficking refers to the commercial exploitation of people through force, fraud, or coercion. Policy and research focus on two forms of trafficking: labor and sex trafficking, which ensnare people in modern forms of slavery or debt servitude. Labor trafficking is broad in scope and includes forced work in any industry. Sex trafficking refers specifically to forced sex work.

Understanding the extent of human trafficking is challenging for several reasons. Trafficking typically happens through clandestine networks. Individuals, families, and businesses who enslave others often seem legitimate. People who experience trafficking are often among the most socially and economically vulnerable. Even if they have opportunities to report their situation, they may not for fear of retaliation.

The United States operates a national hotline through which people can report suspected trafficking or seek help. The hotline publishes data on human trafficking cases and trafficked people that have been identified from hotline reports.

Hotline data spanning 2015 through 2021 indicate that the reported number of people experiencing trafficking nationwide rose from 12,000 in 2015 to more than 22,200 in 2019 and then fell to 16,700 in 2021. In California, these numbers peaked a year earlier and more modestly, so that California now accounts for smaller shares of trafficking cases and trafficked people. In 2015, 18% of trafficking cases and 15% of trafficked people were in California. By 2021, 13% of both cases and people were in California.

Nearly nine in ten reported human trafficking cases involve sex trafficking—and that share has risen. Between 2015 and 2021, the share of human trafficking cases that involved sex trafficking grew from 87% to 89% in California and from 85% to 88% nationally. Statewide and nationally, sex trafficking is most common in pornography, massage parlors, and hotels. Among those trafficked for their labor, about one in five work in private homes.

People who experience trafficking overwhelmingly identify as female. However, the share of trafficked people who are female has decreased, nationally and statewide. In 2015, 91% of trafficked people in California and 89% nationally were women. By 2021, those shares had fallen to 86% and 85%, respectively.

Nearly half of people trafficked in California are US citizens. However, the foreign-born share of trafficked people has risen dramatically. In California, the share of trafficked people born outside the US rose from 36% in 2015 to 54% in 2021. Nationally, the share of trafficked people who were born elsewhere escalated from 38% to 62%.

The first federal law to address human trafficking was passed in 2000. California followed suit in 2005. Nearly all states now have laws prohibiting sex and labor trafficking. Yet the Bureau of Justice Statistics has only recently begun to produce national data about trafficking cases and how state attorneys general handle them. Although the California attorney general has made combatting human trafficking a top priority, the state has not yet contributed to this national effort.

Limited state and national data on human trafficking and how it is handled hamper efforts to address it. In 2021, the Biden Administration updated the National Action Plan to Combat Human Trafficking to include a four-part strategy of prevention, protection, prosecution, and partnership. Ensuring the success of each of these arms will require gathering and disseminating information about traffickers, people experiencing or at risk of experiencing trafficking, and evaluating whether individual practices and policy interventions reduce human trafficking.