A record number of online returns has created a booming $644 billion liquidation market. As supply chain backlogs cause shortages of new goods and Gen Z shoppers demand more sustainable retail options, pain points for one sector of retail are big business for another. The nation’s only major public liquidator, Liquidity Services, resells unclaimed mail, items left at TSA checkpoints, and outdated military vehicles. It also refurbishes highly sought after electronics, from noise-canceling headphones to the machines that make microchips.

CNBC takes you on an exclusive tour inside a Liquidity Services returns warehouse outside Dallas, Texas, where unwanted goods from Amazon and Target are stacked to the ceiling before being resold on Liquidation.com or a variety of other marketplaces. Inside Liquidity Services’ 130,000-square-foot warehouse in Garland, Texas, the aisles aren’t lined with typical merchandise. Instead, they’re stacked with returns from Amazon, Target, Sony, Home Depot, Wayfair and more, all in the process of being liquidated.