In a report Tuesday, the American Trucking Association said its seasonally adjusted For-Hire Truck Tonnage Index rose 2.8% in December after surging 3.9% in November.

"The back-to-back increases in November and December were by far the best gains of 2012," the report said.

Swift's shares were up more than 26% to a 52-week high in Thursday afternoon trading after the trucker crushed fourth-quarter estimates late Wednesday. Swift said EPS rose 31% to 38 cents, beating the consensus of 19 analysts polled by Thomson Reuters by 12 cents.

Swift, which has a fleet of about 12,000 tractors and 51,000 trailers, said sales advanced 7% compared to Q4 last year. Wall Street expected $881.4 million.

In a letter to shareholders after it announced results, Swift said, "Our key trucking metrics are trending favorably, despite economic uncertainty, and we have seen strong growth in our intermodal and Dedicated segments."

Larger rival J.B. Hunt, whose fleet of 10,000 trucks and tractors and more than 75,000 trailers haul goods in the U.S., Canada and Mexico, said Q4 EPS swelled 15% to 70 cents. That beat estimates by a penny.

Revenue grew 11% to $1.34 billion, edging views of $1.33 billion.

Highly rated Hunt's stock has an IBD Composite Rating of 88, meaning it's outperformed 88% of all stocks on key metrics such as sales and profit growth. Hunt was up 7% to a record high.

Shares of Old Dominion Freight Lines ( ODFL ), one of the top-rated companies in IBD's Transportation-Truck group, were up about 2% to a new high intraday. Old Dominion sports an IBD Composite Rating of 91. IBD recommends investors pick stocks with Composite Rating of 95 or higher for stock watch lists .

Meanwhile, Union Pacific EPS rose 10% to $2.19, beating analyst predictions by 3 cents. But revenue grew 2.7% to $5.25 billion, below views for $5.31 billion. That was the fourth straight quarter of decelerating revenue growth.

Shares fell 1.3%, but from Wednesday's record high.

Chief Financial Officer Rob Knight said on a conference call with analysts, "We are expecting to see many of the same challenges we faced last year." Union Pacific expects Q1 coal volume to fall in the midteens and for agricultural goods volume to decline in the high-single digits.

Still, Knight said he thinks the company can post higher volume in 2013 if the U.S. and global economies improve.

On Tuesday, Kansas City Southern ( KSU ), CSX ( CSX ) and Norfolk Southern ( NSC ) reported Q4 earnings. All three posted higher profit than expected. But while Kansas City Southern reported slightly faster sales growth for a second straight quarter, CSX and Norfolk yet another revenue decline.

Meanwhile, shares of global shipping giants FedEx ( FDX ) and UPS ( UPS ) both rose more than 2% Thursday intraday, hitting multiyear highs Thursday amid evidence that the U.S. and global economy are improving.