In the U.S., the U.S. Department of Transportation (USDOT) is a federal cabinet department.  The USDOT was established by an act of Congress in 1967.  The mission of the USDOT is twofold.  Firstly, to serve the U.S. by ensuring a fast, safe, efficient, accessible, and convenient transportation system that meets our vital national interests.  Secondly, to enhance the present and future quality of life of Americans[i].

The USDOT is an executive department of the U.S. government administered by the U.S. Secretary of Transportation.  The secretary is appointed by the President, by and with the advice and consent of the Senate.  The key officials of the USDOT are: Deputy Secretary of Transportation, Under Secretary for Policy, General Counsel, Assistant Secretary for Budget and Programs, Assistant Secretary for Transportation Policy, Assistant Secretary for Governmental Affairs, and Assistant Secretary for Aviation and International Affairs[ii].
The functions of the USDOT are to[iii]:

• ensure the coordinated and effective administration of the transportation programs of the U.S. government;
• Facilitate the development and improvement of coordinated transportation service to be provided by private enterprise to the greatest extent feasible;
• encourage cooperation of Federal, State, and local governments, carriers, labor, and other interested persons to achieve transportation objectives;
• stimulate technological advances in transportation, through research and development or otherwise;
• provide general leadership in identifying and solving transportation problems; and
• develop and recommend to the President and Congress transportation policies and programs to achieve transportation objectives considering the needs of the public, users, carriers, industry, labor, and national defense.

The main divisions of the USDOT are[iv]:

1. Federal Railroad Administration (FRA).  The function of the FRA is to carry out all railroad safety laws of the U.S[v].

2. Federal Highway Administration (FHWA). The FHWA provides for highway safety programs, research, and development related to highway design, construction and maintenance, traffic control devices, identification and surveillance of accident locations, and highway-related aspects of pedestrian safety[vi].

3. The National Highway Traffic Safety Administration (NHTSA) is an agency of the executive branch of the U.S. government assigned to improve the safety of commercial motor vehicles[vii].

4. The Federal Aviation Administration (FAA) is an agency of the USDOT with authority to regulate and oversee all aspects of civil aviation in the U.S[viii].

5. The Federal Transit Administration (FTA) is an agency within the USDOT providing financial and technical assistance to local public transit systems[ix].

6. The Pipeline and Hazardous Materials Safety Administration (PHMSA) is the federal agency charged with the nation’s safe and secure movement of shipments of hazardous materials by all modes of transportation.  The agency also oversees the nation’s pipeline infrastructure[x].

7. The Maritime Administration is an agency of the USDOT that maintains the National Defense Reserve Fleet (NDRF) as a ready source of ships for use during national emergencies[xi].

8. The Saint Lawrence Seaway Development Corporation (SLSDC) is responsible for the safe and efficient movement of marine traffic through the U.S.-owned and operated facilities of the Saint Lawrence Seaway[xii].

9. The Federal Motor Carrier Safety Administration (FMCSA) regulates the trucking industry in the U.S[xiii].

10. The Office of Inspector General (OIG) is charged with monitoring and auditing the USDOT programs to combat waste, fraud, and abuse.

11. The Office of the Secretary of Transportation (OST) develops and coordinates policies for an efficient and economical national transportation system, with due regard for need, the environment, and national defense.

12. The Research and Innovative Technology Administration (RITA) manages research and implements cost reduction technologies within the USDOT.

13. The Surface Transportation Board (STB) is a bipartisan, decisionally-independent adjudicatory body organizationally housed within the USDOT.

United States Department of Transportation

[i] 49 USCS § 101.

[ii] 49 USCS § 102.

[iii] 49 USCS § 101.

[iv] 49 USCS § 106.

[v] 49 USCS § 103.

[vi] 49 USCS § 104.

[vii] 49 USCS § 105.

[viii] 49 USCS § 106.

[ix] 49 USCS § 107.

[x] 49 USCS § 108.

[xi] 49 USCS § 109.

[xii] 49 USCS § 110.

[xiii] 49 USCS § 113.