Deeper strains are starting to turn up in peak-season supply chains, reports The Wall Street Journal. A backup of 40 container ships has grown off Georgia’s Port of Savannah, raising fresh concerns that goods arriving for the fall will face new delays as operators scramble to keep shipments moving.

Georgia Ports Authority officials say the backlog has grown in part because of constraints in berth capacity during a construction project and because retailers have been ordering goods early to ensure their shelves are stocked this fall.

The new backup at the fourth-largest U.S. gateway for seaborne container imports comes as bottlenecks in Southern California have extended to rail services and into overfilled container yards at Midwest hubs.

North of Savannah, South Carolina’s Port of Charleston says ships are moving without delay. But for most shippers, relief from congestion may only come if inventory-laden big retailers pull back their orders.