Library of Congress

The Library of Congress is the research library of the United States Congress, de facto national library of the United States and the oldest federal cultural institution in the United States. Located in four buildings in Washington, D.C., as well as the Packard Campus in Culpeper, Virginia, it is the largest library in the world by shelf space and number of books.

The Library's primary mission is researching inquiries made by members of Congress through the Congressional Research Service. It also serves as the legal repository for copyright protection and copyright registration for the United States Copyright Office.

Ask a Library of Congress Librarian
http://www.loc.gov/rr/askalib/