The For-Hire Truck Tonnage Index decreased 3.1% in February to 131.6, the lowest level since September of last year. Winter weather, slow retail sales, and other industries were to blame for the slow month.

Compared with February of last year, the seasonally adjusted index increased 3% but the ATA pointed out that this was the smallest year-over-year gain since June 2014 and below the 2014 annual increase of 3.7%. Without being seasonally adjusted, the index equaled 118.9 which was 6.4% lower than in January.

“The February drop in truck tonnage was not a surprise,” said Bob Costello, ATA chief economist. “Retail sales, manufacturing output and housing starts were all off during the month so the tonnage decline fits with those indicators.”

Costello indicated that winter had impacted a large portion of the country in February negatively impacting truck tonnage and industries that drive tonnage.

ATA calculates the tonnage index based on surveys from its membership and has been doing so since the 1970s. The report includes month-to-month and year-over-year results, relevant economic comparisons, and key financial indicators.