Freight carried by the for-hire transportation industry fell 1.8% in May from April, falling for the second consecutive month, according to the U.S. Department of Transportation's Bureau of Transportation Statistics' Freight Transportation Services Index.

BTS, a part of the Research and Innovative Technology Administration, reported that freight shipments in May measured by the Freight TSI dropped to their lowest level since November 2010.

The Freight TSI measures the month-to-month changes in freight shipments in ton-miles, which are then combined into one index. The index measures the output of the for-hire freight transportation industry and consists of data from for-hire trucking, rail, inland waterways, pipelines and air freight.

Freight shipments have increased in 17 of the last 25 months but declined in three of the past four months. Shipments rose 12% over the last 25 months, starting in May 2009, after declining 15.7% in the previous 15 months beginning in February 2008.

In May 2011, freight shipments returned to about the same level as October 2008 when the amount of freight shipped was early in its decline. For the first five months of 2011, freight shipments measured by the index were down 1.2 percent.

Freight shipments in May rose 12% from the recent low in April 2009. In April 2009, freight shipments were at their lowest level since June 1997. The May 2011 level is down 6.8% from the historic freight shipment peak reached in January 2005.