The American Trucking Associations’ For-Hire Truck Tonnage Index fell by 0.9% in August when compared to strong July numbers.

Despite the dip, the index equaled 134.2 and is still up by most other measures. The index increased 2.1% year-over year and is up 3.3% from the start of the year. The not seasonally adjusted index, which represents the change in tonnage actually hauled by fleets before any seasonal adjustment, equaled 137.0 in August. This is 0.5% lower than it was in July.

“After such a robust July, it is not too surprising that tonnage took a breather in August,” said Bob Costello, ATA chief economist. “The dip after a strong gain goes with the up and down pattern we’ve seen this year.”

Contributing factors to the slight decrease include soft housing starts and falling factory output, according to ATA.

“As I said last month, I remain concerned about the high level of inventories throughout the supply chain,” said Costello. “This could have a negative impact on truck freight volumes over the next few months.”