Some economists say as the trucking industry -- one closely related to the agriculture sector -- goes, so goes the economy in general. And, if recent numbers are any indication, the economy could be on its way to recovery.

Recent numbers from the American Trucking Association (ATA) show a relatively big month-over-month jump in tonnage hauled by for-hire truckers at the tail end of 2011; December saw a 6.8% increase in tonnage over November. That puts overall 2011 tonnage almost 6% higher than 2010.

"While I'm not surprised that tonnage increased in December, I am surprised at the magnitude of the gain," says ATA chief economist Bob Costello. "Not only did truck tonnage increase due to solid manufacturing output in December, but also from some unlikely inventory restocking. Inventories, especially at the retail level, are exceedingly lean, and I suspect that tonnage was higher than expected as the supply chain did some restocking during the month."

Including agricultural goods, ATA shows the U.S. trucking industry accounted for just over 67%, or just over 9 billion tons, of the tonnage moved by all modes of moving domestic freight.