The American Trucking Associations' advanced seasonally adjusted for-hire Truck Tonnage Index dropped 3 percent in December as automakers trimmed production.

December's reduction, which followed a 2.3 percent gain in November, marks the first tonnage decline since August and represents the largest monthly contraction of 2005. On a seasonally adjusted basis, the tonnage index fell to 113.3 (2000=100) from 116.9 in November.  On a not-seasonally adjusted basis, the tonnage index contracted by 8.1 percent from November to 106.2.
Despite the monthly decline, the December tonnage index stands 0.6 percent higher than a year earlier. For all of 2005, the index increased 2.0 percent compared with 2004.
ATA Chief Economist Bob Costello said weakness in the automotive sector likely impacted December's tonnage reading. He also noted that while total manufacturing output was solid late last year, manufacturing output – when recalculated based on its importance to truck tonnage rather than value – was not quite as strong.  In December, the truck tonnage-weighted manufacturing index contracted 0.4 percent from November 2005. December's figure grew just
0.6 percent from a year earlier – well below the 4.1 percent gain in the Fed-reported index.
"The magnitude of December's reduction came as a surprise," Costello said.  "However, I continue to believe that tonnage will grow in 2006 and that the latest reading should not cause people in the industry to panic. The tonnage index gained 2 percent in 2005, which is good considering capacity growth was very limited all year."
Trucking serves as a barometer of the U.S. economy because it represents nearly 70 percent of tonnage carried by all modes of domestic freight transportation, including manufactured and retail goods.
Trucks hauled 9.8 billion tons of freight in 2004. Motor carriers collected $671 billion dollars, or just under 88 percent of total revenues 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 tenth day of the month.  The report includes month-to-month and year-over-year results, relevant economic comparisons, and key financial indicators.