• The Federal Aviation Administration (FAA) oversees the safety of civil aviation.

• The Federal Highway Administration (FHWA) coordinates highway transportation programs in cooperation with states and other partners.

• The Federal Motor Carrier Safety Administration reduces commercial motor vehicle-related fatalities and injuries.

• The Federal Railroad Administration (FRA) promotes safe and environmentally sound rail transportation.

• The Federal Transit Administration (FTA) assists in developing mass transportation systems.

• The Maritime Administration (MARAD) promotes development and maintenance of an adequate, well-balanced, United States merchant marine.

• The National Highway Traffic Safety Administration (NHTSA) is responsible for reducing deaths, injuries and economic losses resulting from motor vehicle crashes.

• The Pipeline and Hazardous Materials Safety Administration (PHMSA) protects people and the environment from the risks inherent in transportation of hazardous materials.

• The Research and Innovative Technology Administration (RITA) works to ensure that the nation's transportation research investments produce results for the American people. RITA includes the VOLPE National Transportation Systems Center.

• The Saint Lawrence Seaway Development Corporation (SLSDC) operates and maintains a waterway between the Great Lakes and the Atlantic Ocean.

• The Surface Transportation Board (STB) is the economic regulator of interstate surface transportation, primarily railroads, within the United States.

• Officer of the Inspector General, US DOT

• Office of the Secretary, US DOT

• Working Capital Fund of US DOT

• Chief Financial Officer, US DOT