It’s a traffic jam of epic proportions as dozens of cargo ships are lined up waiting their turn for unloading. Offshore from the Port of Los Angeles, 66 ships carrying tens of thousands of shipping containers stretch for miles down the coast. It’s not just a West Coast problem — New York Harbor is also backed up. The shipping delays are caused by a mixture of Americans buying more, and staffing shortages at ports and in trucking companies. Experts say you should start holiday shopping now.