Freight trains are characterized by having freight cars. Cars are often referred to as wagons, the most common type being a container wagon. Containers can be moved on and off the train by crane and loaded on to ships or trucks. Trains transport much of the world's freight. Most of the rail track in the United States is used to transport cargo, and passenger train service is pale in comparison. Typically, transporting freight by train is more efficient than road transport especially when traveling long distances. Many governments are encouraging that more freight be moved by train because of the environmental benefits that coincide such as reduced emissions and fuel savings.