Newly released figures show the value of freight moved between the U.S. and its North American Free Trade Agreement neighbors totaled $96.1 billion in March, a 5.3% decline from a year ago, but three out of five transportation modes carried more cross-border cargo.

The decline in value, according to the U.S. Transportation Department, was due to the reduced unit price of mineral fuel shipments.

In March 2015 compared to March 2014, the value of commodities moving by air grew by the largest percentage of any mode, 6%. Rail freight increased by 1.5% and truck freight increased by 0.9% Vessel freight and pipeline freight each posted double-digit declines.

Trucks carried 64% of U.S.-NAFTA freight and were the most heavily utilized mode for moving goods to and from both U.S.-NAFTA partners.

Trucks accounted for $30.6 billion of the $51.2 billion of imports, 59.8%, and $30.9 billion of the $44.9 billion of exports, 68.9%. Rail remained the second largest mode, moving 15.8% of all U.S.-NAFTA freight.

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 $50.8 billion in March, down 2.9% from a year earlier. A drop in bidirectional trade of vehicles and parts contributed to a 3.4% decline in U.S.-Canada truck freight over the same time period.

In March, the top commodity category transported between the U.S. and Canada was vehicles and parts, of which $5.4 billion, or 59.2% moved by truck. Mineral fuels had been the top commodity by value moved between the U.S. and Canada for 29 consecutive months. 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 58.4% of the $50.8 billion of freight to and from Canada, followed by rail at 16.7%.

The surface transportation modes of truck, rail and pipeline carried 84.1% of the total U.S.-Canada freight flows

U.S.-Mexico Freight

U.S.-Mexico freight totaled $45.2 billion in March as three out of five transportation modes (air, rail, and truck) carried more U.S.-Mexico freight than in March 2014. Freight carried truck freight increased by 5.3%

Trucks carried 70.3% of the $45.2 billion of freight to and from Mexico, followed by rail at 14.9%.

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 March 2015 was vehicles and parts, of which $4.2 billion, or 48.9%, moved by truck and $3.8 billion, or 45.1%, moved by rail.