Black Friday might mark the semi-official start of the holiday shopping season, but the holiday shipping season has been underway for months as retailers have been bringing products in from overseas. This year, much of that shipping happened even earlier than usual as importers attempted to frontload orders ahead of tariffs. 

“A lot of the high highs through this year have led to some of the lowest lows that we've seen towards the end of the year,” said Weston LaBar, chief strategy officer of Waterfront Logistics, a supply chain logistics company in Southern California. “If we're not seeing imports coming in, it means that people are not ordering those retail goods at the clip that we think.”

LaBar spoke with “Marketplace” host Kai Ryssdal about why he’s particularly worried that empty containers are piling up in Southern California this year.

Click the audio player above to listen to the full conversation.