RETAIL imports through major US ports are expected to grow 4.9 per cent year on year in the first half, according to the monthly Global Port Tracker commissioned by the National Retail Federation (NRF).

"We're forecasting significant sales growth this year and that means retailers will have to import more merchandise to meet consumer demand," said NRF vice president Jonathan Gold.

"With the benefits of pro-growth tax reform coming on top of solid fundamentals like higher employment and improved confidence, we expect a good year ahead," he said.

The import projection comes a day after NRF forecast that 2018 retail sales will grow between 3.8 and 4.4 per cent over 2017's US$3.53 trillion.

Ports covered by Global Port Tracker handled 1.72 million TEU in December, the latest month for which actual results are available. With most holiday merchandise already in the country by then, the number was down 2.1 per cent from November.

The total for 2017 was 20.5 million TEU, topping 2016's record 19.1 million TEU by 7.6 per cent.

January was estimated at 1.77 million TEU, up 4.1 per cent year on year. February is forecast at 1.67 million TEU, up 14.8 per cent; March at 1.54 million TEU, down 1.1 per cent; April at 1.71 million TEU, up 4.8 per cent; May at 1.8 million TEU, up 2.8 per cent and June at 1.8 million TEU, up 4.9 per cent.

The February and March percentages are skewed because of changes in when Asian factories close for Lunar New Year each year. Those numbers would bring the first half of 2018 to a total of 10.3 million TEU, an increase of 4.9 per cent.

All of the numbers above are slightly higher than reported in previous Global Port Tracker news releases because Florida's Port of Jacksonville has been added to the report beginning this month to reflect its growing importance as a container port.

Hackett Associates Founder Ben Hackett, who directs the research for the report, said: "It's clear that 2017 turned out to be a remarkable year in terms of import container volume. That level of growth is difficult to sustain, however, and our models suggest that 2018 will continue to expand but only at about half that pace despite strong fundamentals that indicate a healthy economy and continued growth in consumer spending."

Global Port Tracker, which is produced for NRF by the consulting firm Hackett Associates, covers Los Angeles/Long Beach, Oakland, Seattle/Tacoma on the West Coast; New York/New Jersey, Port of Virginia, Charleston, Savannah, Port Everglades, Miami, and now Jacksonville.