What is an "agency"?
Foia defines an agency as -
The agencies, offices and departments of the Executive branch of the federal government such as the Defense Department, the Office of Management and Budget, and the National Security Council
The independent federal regulatory agencies such as the Federal Trade Commission or the Environmental Protection Agency and the Federal Communications Commission
Federal government-controlled corporations such as the U.S. Postal Service, the Tennessee Valley Authority, the Smithsonian Institution, the National Railroad Passenger Corporation (Amtrak) and others
Additional independent federal regulatory agencies are the Nuclear Regulatory Commission and the Federal Communications Commission.
Although FOIA applies only to agencies of the federal government, every state has laws guaranteeing citizens access to the records of state agencies.