Trucking increased its dominance over other transportation modes in December when it comes to hauling freight between the U.S. and its North American Free Trade Agreement partners, Canada and Mexico.

A new U.S. Transportation Department report shows trucks carried 57.2% of the $90.1 billion of U.S.-NAFTA trade in December 2013, accounting for $26.3 billion of exports and $25.2 billion of imports. This is a 7.2% increase from December 2012 while rail declined 2.3%. Vessel rose 10.7% and air declined 3.2%.

While the value of freight carried by rail decreased during the period, rail was still the second largest mode, at 14.9%, followed by vessels at 11.2%, pipeline at 7.7% and air at 4%. The surface transportation modes of truck, rail and pipeline carried 79.7% of the total NAFTA freight flows.

Total NAFTA trade during December increased 6.4% from a year earlier while suface trade gained 6.5% during the same time. The total value of NAFTA trade during the month increased 3.5 from December 2012.

U.S.-Canada trade by pipeline increased the most of any mode from December 2012 to December 2013, growing 21.9%. For trade with Canada in December, trucks carried 52.2% of the $50 billion of freight, followed by rail at 15.7%, pipelines at 13.2%, vessel at 7.1% and air at 4.7%. The surface transportation modes of truck, rail and pipeline carried 81.2% of the total U.S.-Canada freight flows.

The value of U.S.-Mexico trade by pipeline had the largest percentage increase of any mode from December 2012 to December 2013, growing 17.5%. Freight moved by vessel and air between the U.S. and Mexico increased by 14.8% and decreased by 0.2%, respectively, while trucks gained 9.8%.

For trade with Mexico in December, trucks carried 63.3% of the $40.1 billion of the freight, followed by vessel at 16.4%, rail at 13.8%, air at 3.1% and pipelines at 0.8%. The surface transportation modes of truck, rail and pipeline carried 77.9% of the total U.S.-Mexico freight flows.

In December 2013, the top commodity group transported between the U.S. and Canada was mineral fuels, of which $6.6 billion moved by pipeline. The top commodity category transported between the U.S. and Mexico in December 2013 was electrical machinery, of which $7.2 billion moved by truck.