The value of freight moved between the U.S. and its next door neighbors Canada and Mexico totaled $93 billion in July 2015. All modes except air carried less freight than in July 2014, leading to 8% year-over-year decline, according to new U.S. Transportation Department statistics.

The main reason was a large decrease in the value of commodities moved by pipeline and vessel in July due to the reduced price of mineral fuel, though a decline in the value of freight shipments does not necessarily mean there was a lower volume of freight.

During July, compared to a year earlier, the value of commodities moving by air increased by 3.4%, while truck decreased by 0.6% and rail fell 14.5%. Vessel freight and pipeline freight values fell much more.

Despite a decline in value, trucks carried 63.9% of U.S.-North American Free Trade Agreement (NAFTA) freight and were the most heavily used mode for moving goods to and from both U.S.-trading partners. Trucks accounted for $30 billion of the $49.2 billion of imports, or 61%, and $29.4 billion of the $43.8 billion of exports, or 67.1%.

Rail remained the second largest mode by value, moving 13.7% of all U.S.-NAFTA freight.

U.S.-Canada Freight Drops 14%

The value of U.S.-Canada freight totaled $47.5 billion in July 2015, down 14% from July 2014. No mode of transportation carried a higher value of U.S.-Canada freight than the same time last year.

Lower mineral fuel prices contributed to the decrease, though a large share is moved by vessel and pipeline, which were down by more than a quarter to more than one third.

Trucks carried 57.5% of the $47.5 billion of freight to and from Canada, followed by rail at 14.3% The surface transportation modes of truck, rail and pipeline carried 82.8% of the total U.S.-Canada freight flows.

U.S. truck imports by value with Canada fell 1.7% in July from a year ago while exports declined 9.6%.

In July, the top commodity category for all modes transported between the U.S. and Canada was mineral fuels, of 61.3% moved by pipeline and 22.7% moved by vessel.

U.S.-Mexico Freight Edges Down 0.8%

The value of U.S.-Mexico freight totaled $45.5 billion in July 2015, down 0.8% from July 2014. Only two out of five transportation modes, air and truck, carried more U.S.-Mexico freight than in July 2014.

Year-over-year, the value of U.S.-Mexico air freight rose 9.5%, the largest percentage increase of any mode while freight carried by truck increased by 4.7%.

Trucks carried 70.6% of the $45.5 billion of freight to and from Mexico, followed by rail at 13.1%. The surface transportation modes of truck, rail and pipeline carried 84.6% of the total U.S.-Mexico freight flows.

U.S. truck imports by value with Mexico increased 5.6% while exports added 3.6% in July from a year earlier.

The top commodity category for all modes transported between the U.S. and Mexico in July 2015 was electrical machinery, of which 92.2% moved by truck.