American Trucking Associations' advanced seasonally adjusted for-hire Truck Tonnage Index decreased 0.8 percent in August after contracting a revised 0.5 percent in July.

On a seasonally adjusted basis, the tonnage index fell to 113.5 (2000=100) from 114.4 in July. The tonnage index in August was 0.7 percent higher than a year earlier. Year-to-date, the truck tonnage index was up 2.2 percent, compared with the same period in 2004. On a not-seasonally adjusted basis, the tonnage index jumped 10.8 percent from July to a record high 123.1.
ATA Chief Economist Bob Costello said the tonnage index slipped for three consecutive months, on a month-to-month basis, totaling 1.5 percent. On a year-over-year basis, the tonnage index increased each month in 2005, excluding April. Industry growth has been modest in recent months, slowing from an 8.6 percent growth rate to below 1.0 percent.
Costello said the manufacturing industry played a significant role in the deceleration in truck tonnage. After recalculating the Federal Reserve's measure for manufacturing output based on truck tonnage, instead of the value of the product, the so-called truck-tonnage weighted manufacturing production index has slowed from 4.0 percent year-over-year growth in January to just 0.1 percent in August. The same index fell 0.1 percent from July to August.
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.