All five major transportation modes, including trucking, carried less freight between the U.S. and its neighbors of Canada and Mexico last year than in 2014, but big-rigs continue to dominate such cargo movements, according to new U.S. Transportation Department figures.

The 7.2% decline in value to $1.1 trillion also includes freight moved by rail, pipeline, vessel and air.

Of all the modes, trucking saw the smallest year-over-year drop in the value of commodities moved, down 0.4%. Air fell 1.8%, rail declined 7.1%, vessel tumbled 29.7% and pipeline plummeted 39.4%.

The decline in the value cross-border freight from 2014 to 2015 was almost entirely due to drops in crude oil and petroleum prices. The value of petroleum-related commodity shipments dropped almost 40% year-over-year, while the value of other freight dropped just 0.9%.

In 2015, petroleum-related commodities comprised 10.8% of the total value of U.S. North American freight, down from 16.6% in 2014.

Trucks carried 64.3% of so-called U.S.-NAFTA (North American Free Trade Agreement) freight last year, a 4.4 percentage point increase from 2014, and continued to be the most heavily used mode for moving goods to and from both U.S.-NAFTA partners. Trucks accounted for $359.8 billion of the $589.9 billion of imports, or 61%, and for $351.9 billion of the $516.4 billion of exports, or 68.2%.

Rail remained the second largest mode, moving 14.9% of all U.S.-NAFTA freight. During the last decade, rail’s percentage share rose 0.2 points, far behind trucking increase of 2.2 percentage points.

Freight With Canada Posts Double Digit Drop

From 2014 to 2015, the value of U.S.-Canada freight flows fell 12.6% to $575.2 billion.

Trucks carried 58.3% of the value of the freight to and from Canada, followed by rail at 15.7%. The truck freight value was a 0.8 percentage point decrease from 2005 but an increase of 4.5 percentage points from the year before.

Michigan led all states in freight with Canada in 2015 with $69.1 billion.

The top commodity category transported between the U.S. and Canada in 2015 was vehicles and vehicle parts (other than railway vehicles and parts), valued at $103 billion with 60% moved by truck.

Mexican Freight Down Just Slightly

The value of U.S.-Mexico freight fell 0.6% to $531.1 billion from 2014 to 2015, as trucks carried 70.9% of the value of the freight to and from Mexico, followed by rail at 14.1%. The truck freight value was a 3.4 percentage point increase from 2014 and was up 3.5 percentage points from 2005.

Texas led all states in freight with Mexico in 2015 with $178 billion.

The top commodity transported between the U.S. and Mexico in 2015 was electrical machinery at $103.8 billion, an increase of 7.5% from 2014, with $95.4 billion or 91.9% moved by trucks.