From "Jefferson's Legacy: A brief history of the Library of Congress"
The office of Librarian of Congress, like the Library of Congress itself, has been shaped by tradition, politics, and strong personalities. Although the Library of Congress was established in 1800, the office of Librarian was not created until 1802. This 1802 law stipulated that the Librarian of Congress was to be appointed by the president---not by the Congress. In fact, Congress had no formal role in the appointment process until 1897, when the Senate gained the privilege of confirming the president's selection. No special qualifications are prescribed by law for the job of Librarian of Congress. Nor is a term of office specified, even though in the twentieth century the precedent seems to have been established that a Librarian of Congress is appointed for life. The office of the Librarian of Congress carried little formal authority until 1897, when the same law that gave the Senate the power to approve a president's nomination of the Librarian gave the Librarian sole responsibility for making the institution's rules and regulations and appointing its staff.
- John J. Beckley (1802–1807)
- Patrick Magruder (1807–1815)
- George Watterston (1815–1829)
- John Silva Meehan (1829–1861)
- John Gould Stephenson (1861–1864)
- Ainsworth Rand Spofford (1864–1897)
- John Russell Young (1897–1899)
- Herbert Putnam (1899–1939)
- Archibald MacLeish (1939–1944)
- Luther H. Evans (1945–1953)
- Lawrence Quincy Mumford (1954–1974)
- Daniel J. Boorstin (1975–1987)
- James H. Billington (1987–present)