American Trucking Associations’ advanced seasonally adjusted For-Hire Truck Tonnage Index increased in May following two consecutive months of decreases.

The index was up 2.7% for the month equaling a reading of 139, up from 135.3 in April when the index fell 1.7%. Compared to May 2015, the SA index jumped 5.7%. From January through May, the Truck Tonnage Index is up 4% compared to the same period in 2015.

Despite the positive month of truck tonnage, ATA analysts were weary of calling it a new trend in the trucking industry’s health.

“Following two consecutive decreases totaling 6%, May was a nice increase in truck tonnage,” said Bob Costello, ATA chief economist. “Better consumer spending in April and May certainly helped, but economic growth remains mixed and I’d expect the recent choppy pattern in tonnage to continue for the next quarter or two.”

Without seasonal adjustment, the change in tonnage actually hauled by fleets equaled 138.9 in May. That was 2.4% above April’s 135.6 reading.

“We recently received good news on the inventory cycle, with the total business inventory-to-sales ratio declining for the first time in nearly a year,” said Costello. “While one month doesn’t make a trend, this was good news for the trucking industry.”