CORRECTED -- The American Trucking Associations' advance seasonally adjusted For-Hire Truck Tonnage Index dropped 1.3% in July after rising a revised 2.6% in June 2011.

June's increase was slightly less than the 2.8% ATA reported on July 26. The latest pullback put the SA index at 114 (2000=100) in July, down from the June level of 115.5.

The not seasonally adjusted index, which represents the change in tonnage actually hauled by the fleets before any seasonal adjustment, equaled 111 in July, which was 9% below the previous month.

Compared with July 2010, SA tonnage was up 3.9%. In June, the tonnage index was 6.5% above a year earlier.

"We had heard that freight weakened from a robust June, that that was true," ATA Chief Economist Bob Costello said. Tonnage has fallen in three of the last four months on a sequential basis.

"Despite a solid June, our truck tonnage index fits with an economy that is growing very slowly," Costello noted. "The good news is that tonnage continues to increase on a year-over-year basis, but it is likely that the rate of growth will moderate in the second half of the year."

Notwithstanding the recent deceleration in load growth, truckload pricing has remained firm, notes transportation analyst Peter Nesvold with Jefferies & Co. Revenue per mile, net of fuel, was up 5.9% year-over-year in June, versus +7.2% in May. Inside the data, however, short-haul (less than 500 miles) pricing is weak, down 5.4% yearly in June, versus -3.9% in May, which was its largest year-over-year reduction since April 2009.

CORRECTED 10 a.m. EDT to make clear that June's index increased rather than decreased.