American Trucking Associations' advanced seasonally adjusted (SA) For-Hire Truck Tonnage Index was down 2.3% in March after decreasing 1.5% in February. In March, the index equaled 113.2 (2015=100) compared with 115.8 in February.

"In March, and really the first quarter in total, tonnage was negatively impacted by bad winter storms throughout much of the U.S.," said ATA Chief Economist Bob Costello. "While I expected tonnage to moderate in the first quarter, the late Easter holiday and the winter storms made it worse. It is likely that tonnage will improve in the second quarter, although year-over-year gains will be significantly below the 2018 annual increase of 6.7%."

February's reading was revised down compared with our March press release.

Compared with March 2018, the SA index increased 1.6%, down from February's 3.9% gain. During the first quarter, tonnage was up 3.8% from the same period in 2018.

The not seasonally adjusted index, which represents the change in tonnage actually hauled by the fleets before any seasonal adjustment, equaled 116.3 in March, 10.3% above February's level (105.5). In calculating the index, 100 represents 2015.

Trucking serves as a barometer of the U.S. economy, representing 70.2% of tonnage carried by all modes of domestic freight transportation, including manufactured and retail goods. Trucks hauled 10.77 billion tons of freight in 2017. Motor carriers collected $700.1 billion, or 79.3% of total revenue earned by all transport modes.

ATA calculates the tonnage index based on surveys from its membership and has been doing so since the 1970s. This is a preliminary figure and subject to change in the final report issued around the 5th day of each month. The report includes month-to-month and year-over-year results, relevant economic comparisons, and key financial indicators.