"Imports have seen good growth over last year and retailers are well-stocked as the holiday season continues," said Jonathan Gold, vice president for supply chain and customs policy. "Holiday merchandise has made it from the ships to the shelves and the rest is up to the shoppers."

The cargo numbers come as NRF predicts that this year's holiday sales will grow 3.9 percent over last year to a total of $602bn. Cargo import figures do not correlate directly with sales because they count only the number of cargo containers, not the value of the merchandise inside them, but are an indicator of retailers' sales expectations.

August, September and October are the months when most of the holiday season's merchandise is brought into the country. The 4.35 million cargo containers handled during those months combined represented a 4.3-percent increase over last year and accounted for 26.8 percent of all retail imports for the entire year.

U.S. ports followed by Global Port Tracker handled 1.43 million twenty-foot equivalent units in October, the latest month for which after-the-fact numbers are available. That was down 0.4 percent from September as the peak shipping cycle wound down but up 6.4 percent from October 2012. One TEU is one 20-foot cargo container or its equivalent.

November was estimated at 1.33 million TEU, up 3.6 percent from last year. December is forecast at 1.31 million TEU, up 1.8 percent from last year. January 2014 is forecast at 1.35 million TEU, up 3.3 percent from January 2013; February at 1.18 million TEU, down 7.8 percent from last year; March at 1.32 million TEU, up 15.9 percent; and April at 1.38 million TEU, up 6.6 percent.

The total for 2013 is forecast at 16.2 million TEU, up 2.3 percent from 2012's 15.8 million TEU. The first six months of 2013 totaled 7.8 million TEU, up 1.2 percent from the first half of 2012.

"The U.S. economy appears to have found a growth spurt," Hackett Associates Founder Ben Hackett said, citing estimated third-quarter gross domestic product growth of 3.6 percent. "The paradox is that consumer spending remains very cautious and does not come anywhere near the expansion of GDP. The reason is the increasing levels of inventory. Despite back-to-school sales, Black Friday, Cyber Monday and regular sales, the inventory-to-sales ratio remains stubbornly high. Hopefully, November and December numbers will show a catch-up that will help reduce the inventories."

Global Port Tracker, which is produced for NRF by the consulting firm Hackett Associates, covers the U.S. ports of Los Angeles/Long Beach, Oakland, Seattle and Tacoma on the West Coast; New York/New Jersey, Hampton Roads, Charleston, Savannah, Port Everglades and Miami on the East Coast; and Houston on the Gulf Coast.

NRF is the world's largest retail trade association, representing discount and department stores, home goods and specialty stores, main street merchants, grocers, wholesalers, chain restaurants and internet retailers from the United States and more than 45 countries.

Source: National Retail Federation