American Trucking Associations’ advanced seasonally adjusted (SA) For-Hire Truck Tonnage Index slipped 1% in March 2017 after a 0.1% decline during February.

In March, the index equaled 137.5 (2000=100), down from 138.8 in February. The all-time high was 142.7 in February 2016.

Compared with March 2016, the SA index rose 0.7%. In February, the index contracted 2.7% on a year-over-year basis. Year-to-date, versus the same three months in 2016, the index is up 0.2%. For all of 2016, tonnage was up 2.5%.

The not seasonally adjusted index, which represents the change in tonnage actually hauled by the fleets before any seasonal adjustment, equaled 143.9 in March, which was 14.6% above the previous month (125.6).

“Like several other economic indicators, March truck tonnage was likely hurt by some late-season winter storms,” said Bob Costello, ATA chief economist. “Despite last month’s dip,  seasonally adjusted tonnage rose 1.2% during the first quarter overall from the previous quarter, and increased 0.2% from the same quarter last year.

“While I’m not expecting a surge in truck tonnage anytime soon, the signs remain mostly positive for freight, including lower inventory levels, better manufacturing activity, solid housing starts and good consumer spending,” he said. “As a result, we can expect moderate growth going forward.”

Trucking serves as a barometer of the US economy, representing 70.1% of tonnage carried by all modes of domestic freight transportation, including manufactured and retail goods. Trucks hauled nearly 10.5 billion tons of freight in 2015. Motor carriers collected $726.4 billion, or 81.2% of total revenue earned by all transport modes.