49 CFR 1.2 - Organization of the Department.
(a) The Secretary of Transportation is the head of the Department.
(b) The Department comprises the Office of the Secretary of Transportation (OST), the Office of the Inspector General (OIG), and the following Operating Administrations, each headed by an Administrator who reports directly to the Secretary:
(1) The Federal Aviation Administration (FAA).
(2) The Federal Highway Administration (FHWA).
(3) The Federal Motor Carrier Safety Administration (FMCSA).
(4) The Federal Railroad Administration (FRA).
(5) The Federal Transit Administration (FTA).
(6) The Maritime Administration (MARAD).
(7) The National Highway Traffic Safety Administration (NHTSA).
(8) The Pipeline and Hazardous Materials Safety Administration (PHMSA).
(9) The Research and Innovative Technology Administration (RITA).
(10) The Saint Lawrence Seaway Development Corporation (SLSDC).