The American Trucking Associations' advanced seasonally adjusted For-Hire Truck Tonnage Index decreased 1.3 percent in May 2007, marking the second consecutive month-to-month drop. In April, tonnage fell 2.2 percent.
On a seasonally adjusted basis, the tonnage index declined to a six-month low of 110.6 (2000 = 100) in May from 112.1 the previous month. Compared with a year earlier, tonnage was down 3.6 percent, the largest year-over-year drop since January 2007. The not seasonally adjusted index increased 6.8 percent from April to 117.9.
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.