Your gateway to many government documents and other multi-media is the Government Printing Office. This office's charge is to provide the American people with authentic documents originating from all branches of the Federal government.
The GPO's home page has a link to FDsys, or Federal Digital System, that "provides free online access to official publications from all three branches of the Federal Government."
As explained by the National Archives & Records Administration
Federal Register, the official daily journal of the Federal Government
Compiliation of Presidential Documents
Government RSS directory
Videos from the US Government
Blogs from the National Archives
Podcasts from the US Government
C-SPAN - Telecasts of the Federal political process
US Government International Radio and Television
State Governments' Images & Multimedia
Original documents and records relating to the federal Executive Branch can be found in a variety of archives and libraries.
For one-stop-searching about a specific administration, the Presidential Libraries would be the best option. See the box below for more information.
Other repositories include:
For State, County, Tribal, and Municipal documents try:
Pikes Peak State College Libraries
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