If the trucking industry is still struggling, it's not for lack of freight to haul.

The American Trucking Associations (ATA) Truck Tonnage Index just concluded its strongest year since 1998.

For-hire truck tonnage in the US rose 0.6% in December, on the heels of a 4.7% spike in November, the ATA reported today. The increases pushed the index 6.2% higher for the full year of 2013, making it the strongest year for US tonnage in 15 years.

The November gain was sharply higher than the 2.7% increase that was first reported by ATA.

"Tonnage ended 2013 on a high note, which fits with many economic indicators as trucking is an excellent reflection of the tangible goods economy," said ATA chief economist Bob Costello. "The final quarter was the strongest we've seen in a couple of years, rising 2.2% from the third quarter and 9.1% from a year earlier." 

Costello reiterated his statement from last month: the tonnage acceleration in the second half of the year is pointing to an economy that is likely stronger than some might believe.

"I'm seeing more broad-based gains now. The improvement is not limited to the tank truck and flatbed sectors like earlier in the year," he said. "With manufacturing and consumer spending picking up, coupled with solid volumes from hydraulic fracturing, I look for tonnage to be good in 2014 as well."