The American Trucking Associations' advance seasonally adjusted (SA) For-Hire Truck Tonnage Index increased 2.2 percent in December after falling a revised 0.6 percent in November. The latest improvement put the SA index at 111.6 (2000=100) in December, which was the highest level since September 2008. In November, the SA index equaled 109.2.

The not seasonally adjusted index, which represents the change in tonnage actually hauled by the fleets before any seasonal adjustment, equaled 107.2 in December, down 1 percent from the previous month.'

Compared with December 2009, SA tonnage climbed 4.2 percent, which was higher than November's 3.3 percent year-over-year increase. For all of 2010, tonnage was up 5.7 percent compared with 2009. In 2009, the index plunged 8.7 percent.

ATA Chief Economist Bob Costello said that December's improvement fits well with the sea-saw pattern that many carriers are reporting. 'Fleets continue to tell me that freight volumes are very choppy ' up one week, but down the next. That is a trend that is likely to continue this year as the economy is not growing across the board yet.' Still, Costello said it was a positive sign for the economy that SA tonnage reached the highest level in 27 months. 'I continue to expect truck freight tonnage to grow modestly during the first half of 2011 and accelerate in the later half of the year into 2012.''

Note on the impact of trucking company failures on the index: Each month, ATA asks its membership the amount of tonnage each carrier hauled, including all types of freight. The indexes are calculated based on those responses. The sample includes an array of trucking companies, ranging from small fleets to multi-billion dollar carriers. When a company in the sample fails, we include its final month of operation and zero it out for the following month, with the assumption that the remaining carriers pick up that freight. As a result, it is close to a net wash and does not end up in a false increase. Nevertheless, some carriers are picking up freight from failures and it may have boosted the index. Due to our correction mentioned above however, it should be limited.

Trucking serves as a barometer of the U.S. economy, representing 68 percent of tonnage carried by all modes of domestic freight transportation, including manufactured and retail goods. Trucks hauled 8.8 billion tons of freight in 2009. Motor carriers collected $544.4 billion, or 81.9 percent of total revenue earned by all transport modes.

ATA calculates the tonnage index based on surveys from its membership and has been doing so since the 1970s. This is a preliminary figure and subject to change in the final report issued around the 10th day of the month. The report includes month-to-month and year-over-year results, relevant economic comparisons, and key financial indicators.