The Freedom of Information Act (FOIA) was enacted in 1966 and provides any person the right to obtain access to Federal agency records, with the exception of those records protected from public disclosure. Congress, the President, and the Supreme Court acknowledge FOIA to be a vital part of our democracy.
A FOIA request can be sent to a Federal agency for any Federal agency record. Requests should be sent to the appropriate agency, and each agency's website contains information about the type of records it holds, allowing the public to determine to whom to make a FOIA request.
FOIA applies to Federal agencies only, so does not apply to the Judicial Branch and the Courts, the Legislative Branch and Congress, or State Governments and Courts.
A quick tip for finding FOIA information by agency:
For fast access to records available for public inspection in accordance with FOIA, do a Google or Bing search like this: electronic reading room department of [fill-in-the-blank!].
You'll find pages like this from the Department of State, or this from the Department of Labor. Or consult the comprehensive legal treatise, Guide to the Freedom of Information Act from the Department of Justice.
Prefer tangible resources? The UW Libraries microfiche collection of Declassified Documents Reference System covers 1942-1991 (materials declassified between 1975-1999) -- only a subset of what is available online. It is accompanied by a CD-ROM index (only available in-house on UW Libraries workstations). Ask for assistance with the CD or print guide at the Government Publications-Maps/ Microforms/Newspapers Help Desk.