By Siddharth Cavale

NEW YORK (Reuters) – The United States' busy ports kicked activity up a notch in November and December, when inbound cargo traffic is set to reach new records, the National Retail Federation (NRF) industry group said on Monday.

Retailers had already been front-loading purchases due to a shortened holiday season and shipping bottlenecks worldwide. However, the prospect of a mid-January port strike and planned tariff increases by President-elect Donald Trump have big importers accelerating their buys.

"The window to front-load goods on vessels arriving before a potential strike is quickly closing. Then there are issues as President-elect Trump promises to increase tariffs," said Jonathan Gold, vice president for supply chain and customs policy at the NRF.

As of November, the International Longshoremen's Association union and the United States Maritime Alliance (USMX) employer group were at odds after temporarily suspending a strike in October. A strike could disrupt activity at ports from Maine to Texas once the contract ends on Jan. 15.

October's three-day strike was the first large-scale strike at East Coast and Gulf Coast ports in nearly 50 years, resulting in a rush of imports to the United States during the summer.

Trump proposed tariffs ranging from 10% to 20% on all imports, and 60% or more on goods from China, adding to retailers' anxiety. From September to mid-November, over 200 companies in the S&P 1500 Index cited tariffs as a concern during conference calls or investor events.

He also promised an additional 25% tariff on goods from Canada and Mexico and a 10% tariff on China unless the three countries take action against illegal immigration and fentanyl trafficking into the U.S.

"Shippers are moving up as much cargo as they can before then,” Gold added.

The NRF, which includes major shippers like Walmart, Target, and Lowe's among its members, reported that November container volumes are expected to reach a record 2.17 million 20-foot equivalent units (TEUs), up 14.4% from a year earlier. December volumes are forecasted to be a record 2.14 million TEUs, a rise of 14% year over year.

According to a previous NRF study, U.S. shoppers could lose up to $78 billion in annual spending power if Trump's tariff proposals on all imports are implemented.