The American Trucking Associations’ advanced seasonally adjusted (SA) For-Hire Truck Tonnage Index decreased 1.5% in June, following a revised 2.9% gain during May. In June, the index equaled 137.2 (2000=100), down from 139.3 in May. The all-time high was 144 in February.

“The seesaw pattern continued again in June with tonnage falling after a good rise in May,” said Bob Costello, ATA chief economist. “On a month-to-month basis, tonnage has been down in three of the last four months, totaling 4.7% since February.

“Looking ahead, I expect the freight environment will remain choppy. The good news for trucking is we are the most diverse mode of all freight transportation sectors between industrial and consumer freight. We are currently benefiting from the consumer side while being hurt on the industrial side. And of course we still have the inventory glut that is weighing down tonnage,” he said.

Compared with June 2015, the SA index rose 2.1%, which was down from May’s 5.9% year-over-year gain. Year-to-date, compared with the same period in 2015, tonnage was up 3.7%. Excluding the large increase in February and compared with the same period in 2015, tonnage was up 2.7%.

The not seasonally adjusted index, which represents the change in tonnage actually hauled by the fleets before any seasonal adjustment, equaled 142.2 in June, which was 2.2% above the previous month (139.1).

Trucking serves as a barometer of the U.S. economy, representing 68.8% of tonnage carried by all modes of domestic freight transportation, including manufactured and retail goods. Trucks hauled just under 10 billion tons of freight in 2014. Motor carriers collected $700.4 billion, or 80.3% of total revenue earned by all transport modes.