American Trucking Associations' advanced seasonally adjusted For-Hire Truck Tonnage Index slipped 2.5% in April, following a 1.1% decline during March. (March's percentage decrease was slightly more than reported in our press release on April 18, 2017.) In April, the index equaled 134 (2000=100), down from 137.4 in March. The all-time high was 142.7 in February 2016.

Compared with April 2016, the SA index fell 1.8%. In March, the index rose 0.6% on a year-over-year basis. Year-to-date, compared with the same four months in 2016, the index is off 0.3%. 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 132.6 in April, which was 7.8% below the previous month (143.8).

"I have to admit that April's contraction is a bit surprising, especially considering the anecdotal reports I've been hearing from fleets regarding freight levels," said ATA Chief Economist Bob Costello. "It's not necessarily that tonnage levels fell in April that is surprising, but the size of the decrease. One explanation is that housing starts fell substantially in April as well, and residential construction generates heavier truck freight.

"Despite the fact that tonnage is down a total of 3.6% over the last three months, I still expect moderate growth going forward as key sectors of the economy continue to improve slowly," he said.

Trucking serves as a barometer of the U.S. 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.