American Trucking Associations’ advanced seasonally adjusted For-Hire Truck Tonnage Index increased 2.4% in September after rising 0.3% in August. In September, the index equaled 112.9 compared with 110.2 in August.

“September’s sequential gain was the largest in 2021,” said ATA Chief Economist Bob Costello in a press release. “It is good that tonnage rose in September, but it is important to note that this is happening because each truck is hauling more, not from an increase in the amount of equipment operated as contract carriers in the for-hire truckload market continue to shrink from the lack of new trucks and drivers.

The drivers of truck freight, including retail, construction, and manufacturing, plus a surge in imports, are helping keep demand high for trucking services, he said.

August’s reading was revised down slightly to 0.3%.

Compared with September 2020, the seasonally adjusted index rose 1.7%, which was the first year-over-year gain since May. In August, the index was down 0.7% from a year earlier. Year-to-date, compared with the same nine months in 2020, tonnage is unchanged.

The not seasonally adjusted index, which represents the change in tonnage actually hauled by the fleets before any seasonal adjustment, equaled 113.2 in September, 1% below the August level (114.3). ATA’s For-Hire Truck Tonnage Index is dominated by contract freight as opposed to spot market freight.