They got stuck in the wrong places. Early in the pandemic, as China shipped huge volumes of protective gear such as masks all over the world, containers were unloaded in places like West Africa and South Asia that don’t send much back to China. So empty containers piled up in those places just as Chinese factories were producing an abundance of other goods destined for North America. With too few shipping containers available, even huge companies like Target and Home Depot have waited weeks or months to get their products onto ships and heading toward stores.
Meanwhile, the ships that are making it to the U.S. are getting stuck in a massive traffic jam at the ports. In Los Angeles and Oakland, California, dozens of ships have anchored out in the ocean for days before they could unload. With many dockworkers and truck drivers in quarantine, fewer people were available to unload and transport goods, contributing to the backup.