American Trucking Assns.' advanced seasonally adjusted for-hire Truck Tonnage Index decreased 0.6% in July, marking its second consecutive monthly contraction after falling 0.2% in June.

On a seasonally adjusted basis, the tonnage index fell to 114.3 (2000=100) from 114.9 in June. July's tonnage index was 0.5% higher than a year earlier. Year-to-date, the truck tonnage index was up 2.4%, compared with the same period in 2004. On a not-seasonally adjusted basis, the tonnage index fell 8.2% from June to 110.9.
ATA Chief Economist Bob Costello attributed July's tonnage drop to several factors, including a 0.1% drop in manufacturing durable goods shipments, as well as relative weakness in manufacturing production, especially in higher weight products like paper.
Costello said recalculating the Federal Reserve's measure for manufacturing output based on truck tonnage, instead of the value of the product, pushed the so-called truck-tonnage weighted manufacturing production index down 0.2% from June to July. The weighted manufacturing production index grew only 0.4% from a year earlier, he said.
Costello recently lowered the trucking industry's 2005 growth projections to between 2.25% to 2.75% from 3% to 3.5%.
"Due to tough upcoming year-over-year comparisons from extremely strong growth in the second half of 2004, as well as modest growth in truck-tonnage weighted manufacturing production, I'm lowering our growth projection for 2005 to the 2.25% to 2.75% range," Costello said.
Trucking serves as a barometer of the U.S. economy because it represents nearly 70% 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% 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.