Import cargo volume at major retail container ports in the US is expected to be up 15% year-on-year in June, with double-digit increases continuing into the autumn as the US economy recovers.

The forecast came as the monthly Global Port Tracker report released by the National Retail Federation (NRF) and Hackett Associates showed that US ports handled 1.15m Twenty-foot Equivalent Units (TEUs) in April, the latest month for which numbers are available.

That was up 7% from March and up 16% from April 2009. It was also the fifth month in a row to show a year-over-year improvement since December. One TEU is one 20-foot cargo container or its equivalent.

“Cargo import numbers are up but retailers are looking closely at other economic indicators to make sure they are sourcing the appropriate amount of merchandise based on consumer demand,” said Jonathan Gold, NRF vice president for supply chain and customs policy.

“Job creation remains a key factor that’s going to affect consumer spending and retail sales.”

May was estimated at 1.16m TEU, a 12% increase over last year as spring products hit store shelves and summer merchandise followed close behind.

June is forecast to remain at 1.16m TEU but the figure would be up 15% from last year. July is forecast at 1.23m TEU, up 11% from last year; August at 1.27m TEU, up 10%; September at 1.31m TEU, up 15%; and October – traditionally the busiest month of the year – at 1.34m TEU, up 12%.

The strong year-over-year increases are partly due to easy comparisons against unusually low numbers last year.

The first half of 2010 is expected to total 6.6m TEU, up 12% from the same period last year. Imports for 2009 totalled 12.7m TEU, down 17% from 2008’s 15.2m TEU and the lowest since the 12.5m TEU reported in 2003.

“Virtually all of the ocean carriers now seem to accept that there will not be a relapse into a second-dip recession nor an end to the growth,” Hackett Associates founder Ben Hackett said, noting that many shipping companies have recently restored services and capacity that had been cut back.