American Trucking Associations‘ advanced seasonally adjusted For-Hire Truck Tonnage Index increased 1.9 percent in October, following a decrease of 0.7 percent during September.

In October, the index equaled 135.7 (with 2000 equaling 100), up from 133.1 in September, and just below the all-time high of 135.8 reached in January 2015.

Compared with October 2014, the index increased two percent, which was above the year-over-year increase of 1.6 percent in September. However, October’s year-over-year gain was well below the year-to-date figure through October, three percent, compared with the same period last year.

The index not seasonally adjusted, representing the change in tonnage actually hauled by fleets before any seasonal adjustment, equaled 139.8 in October, which was 2.1 percent above the previous month (136.9).

“It was good to see tonnage increase nicely in October after contracting a total of 1.6 percent in August and September,” said ATA Chief Economist Bob Costello. “However, tonnage has been overall pretty flat this year, as October’s reading is just shy of January’s level.

“I remain concerned about the high level of inventories throughout the supply chain,” Costello added. “We recently learned that inventories throughout the supply chain and relative to sales rose in September, which is not a good sign. This will have a negative impact on truck freight volumes over the next few months.”

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

ATA calculates the tonnage index based on surveys from its membership and has been doing so since the 1970s. The American Trucking Associations is the largest national trade association for the trucking industry.