Cindy McCain is set Monday to unveil one of a series of digital billboards in Phoenix promoting a telephone hotline for trafficking victims.
Cindy McCain is collaborating with the Polaris Project, an anti-human trafficking nonprofit.
Polaris officials say the 24-hour, confidential hotline leads to the National Human Trafficking Resource Center.
The hotline is for community members who want to give anonymous tips as well as trafficking survivors.
Clear Channel Outdoor, which is donating billboard space, says about 50 billboards in metropolitan Phoenix will feature the hotline.
Cindy McCain chairs the Arizona Governor's Task Force on Human Trafficking.
She has called for Arizona lawmakers to enact tougher penalties for human traffickers.