[CORRECTED] The American Trucking Associations’ seasonally adjusted For-Hire Truck Tonnage Index rose 3.5% to 136.8 in November -- the highest level on record.

The index increased 4.4% compared with last November, representing the second best year-over-year gain in 2014. Year-to-date, compared with the same period last year, tonnage is up 3.3%

The index has been advancing steadily with increases in four out of the last five months for a total gain of 6.4%. The improving economy has strengthened tonnage in the past year, according to the ATA.

“With strong readings for both retail sales and factory output in November, I’m not surprised that tonnage increased as well,” said Bob Costello, ATA chief economist. “However, the strength in tonnage did surprise to the upside.”

The not seasonally adjusted index equaled 125.8 in November, which was 10.5% below the previous month at 140.5.

Trucking serves as a barometer for the U.S. economy, representing 69.1% of tonnage carried by domestic freight transportation. The ATA calculates the tonnage index based on surveys from its membership.

Corrected 12/22/2014 to clarify year-to-date vs. monthly comparisons