The latest gain put the SA index at 115.8 (2000=100) in September, up from the August level of 114. August's decrease was more than the preliminary 0.2% figure ATA reported on Sept. 27.
"I continue to believe the economy will skirt another recession, because truck tonnage isn't showing signs that we are in a recession," said Bob Costello, ATA's chief economist. "Tonnage is suggesting that we are in a weak growth period for the economy, but not a recession."
Costello also noted that the third quarter average exhibited signs of small gains for the broader economy, not contraction.
"In the third quarter, tonnage was up 0.4% from the second quarter. Prior to the two previous recessions, truck tonnage was plummeting, but not this time."
The not-seasonally-adjusted index, which represents the change in tonnage actually hauled by the fleets before any seasonal adjustment, equaled 119.5 in September, which was 3.1% below the previous month, ATA said.
Compared with September 2010, SA tonnage was up a solid 5.9%. In August, the tonnage index was 4.9% above a year earlier.
Trucking serves as a barometer of the U.S. economy, representing 67.2% of tonnage carried by all modes of domestic freight transportation, including manufactured and retail goods. Trucks hauled 9 billion tons of freight in 2010. ATA calculates the tonnage index based on surveys from its membership and has been doing so since the 1970s.