Additional tariff hikes were delayed by President Trump in May after he met with China's President Xi Jinping, saying the move would buy time for trade negotiators. 

Coupled with tariffs imposed over the past year, the new round would have taxed almost all goods the US imports from China, according to the monthly "Global Port Tracker" report. 

US ports covered by the report handled 1.85 million TEU in May, the latest month for which after-the-fact numbers are available. That was up six per cent from April and up 1.4 per cent year on year.

June is estimated to reach 1.87 million TEU, up only 0.8 per cent year on year. July is forecast at 1.93 million TEU, up 1.3 per cent; August at 1.96 million TEU, up 3.4 per cent; September at 1.89 million, up 1.1 per cent; October at 1.94 million TEU, down 4.5 per cent, and November at 1.88 million TEU, up 4.3 per cent.

If born out, the August number would equal the total seen last December just ahead of a scheduled January 1 tariff increase that was ultimately delayed until this spring, and would be second only to the 2 million TEU record set last October, the report said. But the small year-on-year increases expected in the next few months compare with double-digit growth in multiple months last year, when retailers rushed to import Chinese merchandise ahead of expected tariff increases.

"Retailers still want to protect their customers against potential price increases that would come with any additional tariffs, but with the latest proposed tariffs on hold for now and warehouses bulging, there's only so much they can do," said NRF vice president Jonathan Gold. 

"We will still see some near-record numbers this summer, but right now no one knows whether there will be additional tariffs or not. We hope the restarted negotiations with China will result in significant reforms rather than more tariffs that tax American companies and consumers." 

Imports during 2018 set a record of 21.8 million TEU, an increase of 6.2 per cent over 2017's previous record of 20.5 million TEU, the report found. The first half of 2019 totalled an estimated 10.6 million TEU, up 2.8 per cent over the first half of 2018.

"Imports of consumer goods continue to grow as importers purchase items in expectation of further increases in tariffs, the cost of which will be borne by the American consumer," said Hackett Associates founder Ben Hackett. "Trade has become the sharp end of foreign policy, and we continue to believe that this will ultimately damage both sides of the conflict in a lose-lose situation."

The Global Port Tracker covers Los Angeles/Long Beach, Oakland, Seattle and Tacoma; New York/New Jersey, Port of Virginia, Charleston, Savannah, Port Everglades, Miami and Jacksonville and Houston on the Gulf Coast.