The U.S. transportation sector consumes about 220 billion gallons of liquid hydrocarbon fuel per year. Energy use in the transportation sector is primarily for passenger travel and freight movements. Passenger vehicles consist of light-duty vehicles (automobiles, motorcycles, and light trucks) and high-duty vehicles (buses, airplanes, boats, and trains). The freight modes of transport include truck, air, rail, pipeline, and marine (domestic barge and cargo). Energy is also used for military operations and off-highway vehicles used for construction and farming.