Import cargo volume at the nation's major retail container ports is expected to set a new monthly record in October, a new forecast suggests, as the holiday season approaches.

Import volume at US ports is expected to total 1.53m containers this month, topping the 1.52m monthly record set in August, according to the National Retail Federation's Global Port Tracker report.

Volume, the report reveals, has been well above average each month since spring as retailers have imported merchandise early in case of any disruption on the docks.

"Increasing congestion at the nation's ports as well as the ongoing West Coast labour negotiations are ongoing concerns and retailers are making one last push to make sure they're stocked up for the holidays," NRF Vice President for Supply Chain and Customs Policy Jonathan Gold said. "Retailers are working hard to make sure customers can find what they're looking for regardless of what happens at the ports."

The contract between the Pacific Maritime Association and the International Longshore and Warehouse Union expired on 1 July, prompting concerns about potential disruptions that could affect back-to-school or holiday merchandise, the report explained. Dockworkers remain on the job as negotiations continue but the lack of a contract and operational issues have led to record congestion at the ports.