While American Trucking Associations’ advanced seasonally adjusted (SA) For-Hire Truck Tonnage Index decreased 0.7% to 113.5 in May after falling 0.6% to 114.5 in April, the number remains well above the lows of 2020.

“One freight segment that is helping tonnage is gasoline as demand for travel, both commuting and vacation related, picks up,” said ATA Chief Economist Bob Costello in a press release. “I’m also expecting retail freight to remain robust as inventories are at historic lows. As retail stocks are rebuilt, it will boost freight. As has been the case for some time, trucking’s biggest challenges are not on the demand side, but on the supply side, including difficulty finding qualified drivers.”

April’s reading was revised down from 0.3% to 0.6% from ATA’s May 18 press release.

Compared with May 2020, the SA index rose 3.7%, which was preceded by a 6.7% year-over-year jump in April. Year-to-date, compared with the same five months in 2020, tonnage is up 0.4%.

The not seasonally adjusted index, which represents the change in tonnage actually hauled by the fleets before any seasonal adjustment, equaled 113.8 in May, 0.2% below the April level (114). In calculating the index, 100 represents 2015. ATA’s For-Hire Truck Tonnage Index is dominated by contract freight as opposed to spot market freight.

ATA calculates the tonnage index based on surveys from its membership and has been doing so since the 1970s.