It is the largest and most comprehensive library in the world, located in Washington, D.C. The Library of Congress functions as the national library of the United States, although it has never been officially recognized as such through legislation. The library’s primary purpose is to serve the Congress of the United States, but its collections, services, and reading rooms are freely available for use by all persons over high school age. The Library of Congress also serves as the official copyright agency of the United States.
Established by an act of Congress in 1800, the library was first located in the Capitol building in Washington, D.C. Today the Library of Congress occupies three large buildings in the Capitol Hill area of the city, near the Capitol building and the United States Supreme Court building. Approximately 1 million people visit the library each year.
The Library of Congress also works closely with specialized libraries in the executive branch of government that have been designated by Congress as national libraries. These include the National Library of Medicine, the National Agricultural Library, and the National Library of Education.
Through a provision in U.S. copyright law, the Library of Congress is entitled to receive copies of every work registered for copyright in the United States. Copyright deposits make up the core of the general collections. The library's role as the U.S. copyright depository has contributed to the popular belief that it contains one copy of every book published in the United States. It does not. The library is not required to retain all U.S. copyright deposits indefinitely. Through a program in its Exchange and Gift Division, the library shares with other institutions items that are declared surplus to its needs.
The library’s manuscript holdings include the personal papers (letters, diaries, and other documents) of 23 American presidents ranging in time from George Washington (1732-1799) through Calvin Coolidge (1872-1933). (The personal papers of many presidents after Coolidge are contained in the presidential libraries of the National Archives and Records Administration in Washington, D.C.) The Library of Congress manuscript collections also contain the personal papers of other eminent Americans, such as poet Walt Whitman, inventor Alexander Graham Bell, social reformer Susan B. Anthony, humanitarian Clara Barton, abolitionist and writer Frederick Douglass, and composers George Gershwin and Irving Berlin.
Many of the library's foreign languages collections are exceptional. Its foreign newspapers and gazettes are particularly strong. In addition, two-thirds of the library’s 17 million books are in languages other than English. Its Chinese, Russian, Japanese, Korean, and Polish collections are the largest outside of those countries, and the Arabic collections are the largest outside of Egypt. The library’s collection of Hispanic and Portuguese materials is among the largest in the world