Year-over-year cargo volume at the nation’s major retail container ports fell for the 16th straight month in November, leaving 2008 on track to be the slowest year since 2004 as the U.S. economic downturn continues, according to the monthly Port Tracker report released today by the National Retail Federation and IHS Global Insight.

Volume is projected to total 15.3 million Twenty-Foot-Equivalent Units for the year, compared with 16.5 million TEU in 2007. That would be a decline of 7.1% and the lowest total since 2004, when 14 million TEU moved through the ports. The projection for the year is the same as last month after growing from a 6% drop forecast in September and 6.5% drop forecast in October. One TEU is one 20-foot container or its equivalent.

“As retailers face the most challenging holiday season in years, they are being careful with their inventory levels, and that means lower volume at the ports,” NRF Vice President for Supply Chain and Customs Policy Jonathan Gold said. “Cargo volume isn’t a direct correlation with dollar volume of sales, but it’s a good indication of what retailers are thinking.”

US ports surveyed handled 1.36 million TEU in October, the most recent month for which actual numbers are available. October is the traditional peak of the shipping season as retailers stock up on holiday merchandise, and the number was up 2.4% from September but down 5.4% from October 2007. The number is also down from the 2007 peak of 1.48 million TEU set last September. November was estimated at 1.26 million TEU, down 8.5% from November 2007. The last month to see a year-over-year increase was July 2007, when the 1.44 million TEU moved through the ports was up 3.4% from July 2006.

December is forecast at 1.22 million TEU, down 5% from December 2007. January 2009 is forecast at 1.17 million TEU, down 4.9% from a year earlier, and February, traditionally the slowest month of the year, is forecast at 1.11 million TEU, down 9%. A year-over-year increase of 2.5% is forecast in March at 1.19 million, but April is forecast at 1.25 million TEU, down 1.3%.

Meanwhile, Port Tracker’s congestion rating for the Ports of Los Angeles and Long Beach – the nation’s two largest retail container ports – was restored to low. The two ports had been rated at medium the past three months because of the new Clean Truck Program there.

“Startup of the Clean Truck Program regulations has not disrupted cargo, and collection of program and infrastructure fees has been delayed until next year,” IHS Global Insight Economist Paul Bingham said. “The beginning of the slow season in an already weak traffic environment reduces pressure for port truck drivers, so capacity should remain adequate.”

The remainder of the US ports covered by Port Tracker – Oakland, Seattle and Tacoma on the West Coast; New York/New Jersey, Hampton Roads, Charleston and Savannah on the East Coast, and Houston on the Gulf Coast – are rated “low” for congestion, the same as last month.