. The latest reading lands the index at 103.9, down from August's 104.1. (The year 2000 is the base year at 100).
While tonnage was down 7.3 percent from the year-ago month, this is best year-over-year showing since November 2008. In August, the index was down 7.5 percent from a year earlier.
The not seasonally adjusted index, which represents the change in tonnage actually hauled by the fleets before any seasonal adjustment, was up 2 percent from August, to 107.9.
According to ATA Chief Economist Bob Costello, the latest reading is an indicator that the recovery will be moderate and choppy.
"The trucking industry should not be alarmed by the very small decrease in September," Costello said. "We took two steps forward in July and August and this was a miniscule step backward. Between most economic indicators recovering and less of an overhang in inventories, I'm confident that the industry is still on the road to recovery."