The value of U.S.-NAFTA freight totaled $93.3 billion in April, according to new U.S. Transportation Department figures, down 6.8% from the same time a year earlier.

This happened as all modes but air carried less freight between the U.S. and its next-door neighbors of Canada and Mexico.

In April 2015 compared to a year earlier, the value of commodities moving truck and rail each declined 0.9% while air was the only mode that grew, 3%. Vessel freight decreased by 22.8% and pipeline freight fell by 44.9%

Trucks carried 64.2% of U.S.-NAFTA freight and are the most heavily utilized mode for moving goods to and from both U.S.-NAFTA partners during the month. Trucks accounted for 60.8% and 67.9% of imports and exports, respectively.

The surface transportation modes of truck, rail and pipeline carried 84.9% of the total U.S.-NAFTA freight flows.

U.S.-Canada Freight

U.S.-Canada freight totaled $48.8 billion in April, down 12.5% from April 2014, as all modes of transportation carried a lower value of U.S.-Canada freight than a year earlier.

In April the top commodity category transported between the U.S. and Canada was vehicles and parts, of which $5.2 billion, or 58.2%, moved by truck and $3.5 billion, or 39.2%, moved by rail.

Mineral fuels had been the top commodity by value moved between the U.S. and Canada for 29 consecutive months, ending February 2015. This change is due, in large part, to a decline in the unit price of mineral fuels in recent months, according to the U.S. DOT.

Trucks carried 58% of the $48.8 billion of freight to and from Canada, followed by rail, 16.9%; pipeline, 9.1%; vessel, 5.4%; and air, 4.5%.

The surface transportation modes of truck, rail and pipeline carried 84% of the total U.S.-Canada freight flows.

U.S.-Mexico Freight

U.S.-Mexico freight totaled $44.5 billion in April 2015, up 0.3% from April 2014, as three out of five transportation modes – air, rail, and truck – carried more U.S.-Mexico freight.

Year-over-year, the value of U.S.-Mexico air freight rose 17.2%, the largest percentage increase of any mode. Freight carried by rail increased by 7.2% and truck freight added 4.9%. Pipeline freight decreased by 20.8% and vessel freight fell by 32.9%, mainly due to lower mineral fuel prices, said the U.S. DOT.

Trucks carried 70.9% of the $44.5 billion of freight to and from Mexico, followed by rail, 14.3%; vessel, 7.8%; air, 3.5%; and pipeline, 0.7%. The surface transportation modes of truck, rail and pipeline carried 85.9% of the total U.S.-Mexico freight flows.

The top commodity category transported between the U.S. and Mexico in April 2015 was electrical machinery, of which $7.6 billion, or 91.5%, moved by truck.