ANOTHER record breaking number of imports passed through American major container ports showing no sign of a slowdown in consumer demand, according to the US National Retail Federation (NRF).

"Cargo volume is expected to remain high as we head into the peak shipping season, and it is essential that all ports continue to operate with minimal disruption," said NRF vice president Jonathan Gold.

US ports handled 2.4 million TEU in May - up 2.7 per cent from last year - setting a new all-time record number of imported containers in a single month since the NRF began tracking imports in 2002 through Global Port Tracker.

At the nation's busiest port in Los Angeles - the port processed 967,900 containers in May, the third best month of all time. And in the first five months of this year, the Port of Los Angeles is on track to equal last year's record-setting pace.

But despite a record number of containers - the number of cargo ships waiting to dock at the ports in Los Angeles and Long Beach is down from its high of 89 vessels November 2021 to 26 last week.

So while maritime congestion has eased - congestion on land is serious - the number of containers clogging the Port of Los Angeles has risen in the last 30 days to an average of 4.3 days and an average of 7.5 days nearby railyards with the peak dwell time coming in at 11 days.

In October the twin ports of LA and Long Beach announced a "container dwell fee" that has been put on hold through. The plan is to delay fee another week and revisit it then, according to LA port spokesman Phillip Sanfield.

Since the programme was announced - the two ports have seen a combined decline of 27 per cent in cargo on docks, according to the Port of Los Angeles. The fee would charge ocean carriers US$100 per container and $100 additionally for each day the container sits at the port.

Adding to the stress, the current contract between the International Longshore and Warehouse Union which represents about 22,000 US west coast dockers expired on June 30. The union said members will continue to work through the expired contract - as negotiations continue.

Ports surveyed in the report include Los Angeles/Long Beach, Oakland, Tacoma, Seattle Houston, New York/New Jersey, Hampton Roads; Charleston, Savannah, Miami, Jacksonville, Fort Lauderdale and Port Everglades.

For the following months, Port Tracker issued the following projections: June, at 2.25 million TEU, up 4.8 per cent annually, which would increase the first half 2022 total to 13.5 million TEU, for a 5.4 per cent annual increase; July, at 2.31 million TEU, up 5.3 per cent annually, which would be the fourth-busiest month on record; August, at 2.26 million TEU, down 0.5 per cent annually; September, at 2.12 million TEU, down 0.8 per cent annually; October, at 2.12 million TEU, down 4.1 per cent annually; and November, at 2.06 million TEU, down 2.5 per cent annually.