In a sweeping two-year investigation, the AP found that goods linked to the forced labor of US prisoners wind up in the supply chains of a dizzying array of products, from Frosted Flakes cereal and Ball Park hot dogs to Gold Medal flour and Coca-Cola beverages. They're on the shelves of most supermarkets, including Kroger, Target, Aldi, and Whole Foods. Many of the companies buying directly from prisons are violating their own policies against the use of such labor. But it's completely legal, dating back largely to the need for labor to help rebuild the South's shattered economy after the Civil War. Enshrined in the Constitution by the 13th Amendment, slavery and involuntary servitude are banned—except as punishment for a crime. Takeaways from the AP's investigation: