One of biggest US ports will start operating 24 hours a day to try to clear long queues of cargo ships stuck waiting outside.
The Port of Los Angeles in California will handle more goods at night after a similar move by nearby Long Beach port.
The ports - which handle 40% of all cargo containers entering the US - have faced months of problems.
Major US firms such as Walmart and FedEx have also committed to increasing their round-the-clock operations to help clear the jam, the White House said on Wednesday.
What is going on?
Global supply chains have been disrupted as economies have unlocked and consumer demand has roared back.