The trucking industry serves the American economy by transporting large quantities of raw materials, works in process, and finished goods over land—typically from manufacturing plants to retail distribution centers. Trucks are also used in the construction industry, two of which require dump trucks and portable concrete mixers to move the large amounts of rocks, dirt, concrete, and other building materials used in construction. Trucks in America are responsible for the majority of freight movement over land and are tools in the manufacturing, transportation, and warehousing industries.