(1966), executive department of the federal government, responsible for the development and promotion of national transportation policies and programs. Headed by the secretary of transportation, a member of the president's cabinet, the department promotes safety, conducts research, and supervises federal divisions responsible for aviation, highways, railroads, mass transit, and maritime services, as well as the St. Lawrence Seaway Development Corporation, the U.S. Coast Guard, and the National Transportation and Safety Board.
