1800–51: Origins and Jefferson's contribution
James Madison is credited with the idea for creating a congressional library, first making such a proposition in 1783.
 The Library of Congress was established April 24, 1800, when
John Adams signed an
act of Congress providing for the transfer of the seat of government from
Philadelphia to the new capital city of Washington. Part of the legislation appropriated $5,000 "for the purchase of such books as may be necessary for the use of Congress ..., and for fitting up a suitable apartment for containing them...."
 Books were ordered from London and the collection, consisting of 740 books and 3 maps, was housed in the new
Thomas Jefferson played an important role in establishing the structure of the Library of Congress. On January 26, 1802, he signed a bill that allowed the president to appoint an overseer of the Library of Congress (the
Librarian of Congress) and for the establishment of a
Joint Committee on the Library to regulate and oversee the Library. The new law also extended to the president and vice president the ability to borrow books.
In the midst of the
War of 1812, invading British Regulars led a
Burning of Washington in August 1814, including the
Capitol, and destroyed the Library of Congress and its collection of 3,000 volumes.
 These volumes had been left in the Senate wing of the Capitol.
 One of the only congressional volumes to have survived was a government account book of receipts and expenditures for the year 1810.
 It was taken as a souvenir by a British Commander whose family later returned it to the United States government in 1940.
Within a month, former president Jefferson offered to sell his personal library
 as a replacement. In January 1815, Congress accepted Jefferson's offer, appropriating $23,950 to purchase his 6,487 books.
 Some members of the House of Representatives opposed the outright purchase, including
Daniel Webster, a New Hampshire representative who wanted to return "all books of an atheistical, irreligious, and immoral tendency."
 Jefferson had spent 50 years accumulating a wide variety of books in several languages and in many subjects, including philosophy, science, literature, architecture, law, religion, and mathematics. He had also collected books on topics not normally viewed as part of a legislative library, such as cookbooks. However, he believed all subjects had a place in the Library of Congress. He remarked:
"I do not know that it contains any branch of science which Congress would wish to exclude from their collection; there is, in fact, no subject to which a Member of Congress may not have occasion to refer."
Jefferson's collection was unique in that it was a working collection of a scholar, not a gentleman's collection for display. Jefferson's original collection was organized into a scheme based on
organization of knowledge. Specifically, he grouped his books into Memory, Reason, and Imagination, which broke down into 44 more subdivisions. The Library followed Jefferson's organization scheme until the late 19th century, when librarian
Herbert Putnam began work on a more flexible Library of Congress Classification structure that now applies to more than 138 million items. In 1851, a fire destroyed two thirds of the Jefferson collection, with only 2,000 books remaining. In 2008, after working for ten years, the librarians at the Library of Congress had found replacements for all but 300 of the works that were in Jefferson's original collection.
antebellum period was difficult for the Library. During the 1850s the
Smithsonian Institution's librarian
Charles Coffin Jewett aggressively tried to move that organization towards becoming the United States' national library. His efforts were blocked by the Smithsonian secretary
Joseph Henry, who advocated a focus on scientific research and publication and favored the Library of Congress' development into the national library. Henry's dismissal of Jewett in July 1854 ended the Smithsonian's attempts to become the national library, and in 1866 Henry transferred the Smithsonian Institution's library of forty thousand volumes to the Library of Congress.
December 24, 1851, the largest fire in the Library's history destroyed 35,000 books, about two–thirds of the Library's 55,000 book collection, including two-thirds of Jefferson's original transfer. Congress in 1852 quickly appropriated $168,700 to replace the lost books, but not for the acquisition of new materials. This marked the start of a conservative period in the Library's administration by librarian
John Silva Meehan and joint committee chairman
James A. Pearce, who worked to restrict the Library's activities. In 1857, Congress transferred the Library's public document distribution activities to the
Department of the Interior and its international book exchange program to the
Department of State.
Abraham Lincoln's political appointment of
John G. Stephenson as librarian of Congress in 1861 further weakened the Library; Stephenson's focus was on non-library affairs, including service as a volunteer
aide-de-camp at the battles of
Gettysburg during the
American Civil War. By the conclusion of the war, the Library of Congress had a staff of seven for a collection of 80,000 volumes.
 The centralization of copyright offices into the
United States Patent Office in 1859 ended the Library's thirteen-year role as a depository of all copyrighted books and pamphlets.
1865–97: Spofford's expansion
The West façade of the Library of Congress in 1898
The Library of Congress reasserted itself during the latter half of the 19th century under Librarian
Ainsworth Rand Spofford, who directed the Library from 1865 to 1897. Aided by an overall expansion of the federal government and a favorable political climate, Spofford built broad bipartisan support for the Library as a national library and a legislative resource, began comprehensively collecting
American literature, and led the construction of a new building to house the Library, and transformed the Librarian of Congress position into one of strength and independence. Between 1865 and 1870, Congress appropriated funds for the construction of the Thomas Jefferson Building, placed all
copyright registration and deposit activities under the Library's control, and restored the Library's international book exchange. The Library also acquired the vast libraries of both the Smithsonian and historian
Peter Force, strengthening its scientific and Americana collections significantly. By 1876, the Library of Congress had 300,000 volumes and was tied with the
Boston Public Library as the nation's largest library. When the Library moved from the Capitol building to its new headquarters in 1897, it had over 840,000 volumes, 40% of which had been acquired through copyright deposit.
A year before the Library's move to its new location, the Joint Library Committee held a session of hearings to assess the condition of the Library and plan for its future growth and possible reorganization. Spofford and six experts sent by the
American Library Association, including future Librarian of Congress
Herbert Putnam and
Melvil Dewey of the
New York State Library, testified before the committee that the Library should continue its expansion towards becoming a true national library. Based on the hearings and with the assistance of Senators
Justin Morrill of Vermont and
Daniel Voorhees of Indiana, Congress more than doubled the Library's staff from 42 to 108 and established new administrative units for all aspects of the Library's collection. Congress also strengthened the office of Librarian of Congress to govern the Library and make staff appointments, as well as requiring Senate approval for presidential appointees to the position.
The Library of Congress in 1898
The Library of Congress, spurred by the 1897 reorganization, began to grow and develop more rapidly. Spofford's successor
John Russell Young, though only in office for two years, overhauled the Library's bureaucracy, used his connections as a former diplomat to acquire more materials from around the world, and established the Library's first assistance programs for the
blind and physically disabled. Young's successor
Herbert Putnam held the office for forty years from 1899 to 1939, entering into the position two years before the Library became the first in the United States to hold one million volumes.
 Putnam focused his efforts on making the Library more accessible and useful for the public and for other libraries. He instituted the interlibrary loan service, transforming the Library of Congress into what he referred to as a "library of last resort".
 Putnam also expanded Library access to "scientific investigators and duly qualified individuals" and began publishing
primary sources for the benefit of scholars.
Putnam's tenure also saw increasing diversity in the Library's acquisitions. In 1903, he persuaded President
Theodore Roosevelt to transfer by executive order the papers of the
Founding Fathers from the State Department to the Library of Congress. Putnam expanded foreign acquisitions as well, including the 1904 purchase of a four-thousand volume library of
Indica, the 1906 purchase of G. V. Yudin's eighty-thousand volume Russian library, the 1908 Schatz collection of early opera
librettos, and the early 1930s purchase of the Russian Imperial Collection, consisting of 2,600 volumes from the library of the
Romanov family on a variety of topics. Collections of
Hebraica and Chinese and Japanese works were also acquired. Congress even took the initiative to acquire materials for the Library in one occasion, when in 1929 Congressman
Ross Collins of Mississippi successfully proposed the $1.5 million purchase of Otto Vollbehr's collection of
incunabula, including one of three remaining perfect vellum copies of the
In 1914, Putnam established the
Legislative Reference Service as a separative administrative unit of the Library. Based in the
Progressive era's philosophy of science as a problem-solver, and modeled after successful research branches of state legislatures, the LRS would provide informed answers to Congressional research inquiries on almost any topic. In 1965, Congress passed an act allowing the Library of Congress to establish a trust fund board to accept donations and endowments, giving the Library a role as a patron of the arts. The Library received the donations and endowments of prominent individuals such as
John D. Rockefeller, James B. Wilbur and
Archer M. Huntington. Gertrude Clarke Whittall donated five
Stradivarius violins to the Library and
Elizabeth Sprague Coolidge's donations paid for a
concert hall within the Library of Congress building and the establishment of an
honorarium for the Music Division. A number of chairs and consultantships were established from the donations, the most well-known of which is the
Poet Laureate Consultant.
The Library's expansion eventually filled the Library's Main Building, despite shelving expansions in 1910 and 1927, forcing the Library to expand into a new structure. Congress acquired nearby land in 1928 and approved construction of the Annex Building (later the John Adams Building) in 1930. Although delayed during the
Depression years, it was completed in 1938 and opened to the public in 1939.
1939–present: Modern history
When Putnam retired in 1939, President
Franklin D. Roosevelt appointed
Archibald MacLeish as his successor. Occupying the post from 1939 to 1944 during the height of World War II, MacLeish became the most visible Librarian of Congress in the Library's history. MacLeish encouraged librarians to oppose
totalitarianism on behalf of democracy; dedicated the South Reading Room of the Adams Building to Thomas Jefferson, commissioning artist
Ezra Winter to paint four themed murals for the room; and established a "democracy alcove" in the Main Reading Room of the Jefferson Building for important documents such as the Declaration, Constitution and
The Federalist Papers. The Library of Congress even assisted during the war effort, ranging from the storage of the
Declaration of Independence and the
United States Constitution in
Fort Knox for safekeeping to researching weather data on the
Air Force pilots. MacLeish resigned in 1944 to become Assistant Secretary of State, and President
Harry Truman appointed
Luther H. Evans as Librarian of Congress. Evans, who served until 1953, expanded the Library's acquisitions, cataloging and bibliographic services as much as the fiscal-minded Congress would allow, but his primary achievement was the creation of Library of Congress Missions around the world. Missions played a variety of roles in the postwar world: the mission in San Francisco assisted participants in the
meeting that established the United Nations, the mission in Europe acquired European publications for the Library of Congress and other American libraries, and the mission in Japan aided in the creation of the
National Diet Library.
 Evans' successor
L. Quincy Mumford took over in 1953. Mumford's tenure, lasting until 1974, saw the initiation of the construction of the James Madison Memorial Building, the third Library of Congress building. Mumford directed the Library during a period of increased educational spending, the windfall of which allowed the Library to devote energies towards establishing new acquisition centers abroad, including in
Cairo and New Delhi. In 1967, the Library began experimenting with
book preservation techniques through a Preservation Office, which grew to become the largest library research and conservation effort in the United States. Mumford's administration also saw the last major public debate about the Library of Congress' role as both a legislative library and a national library. A 1962 memorandum by Douglas Bryant of the
Harvard University Library, compiled at the request of Joint Library Committee chairman
Claiborne Pell, proposed a number of institutional reforms, including expansion of national activities and services and various organizational changes, all of which would shift the Library more towards its national role over its legislative role. Bryant even suggested possibly changing the name of the Library of Congress, which was rebuked by Mumford as "unspeakable violence to tradition". Debate continued within the library community until the
Legislative Reorganization Act of 1970 shifted the Library back towards its legislative roles, placing greater focus on research for Congress and congressional committees and renaming the Legislative Reference Service to the
Congressional Research Service.
After Mumford retired in 1974, Gerald Ford appointed
Daniel J. Boorstin as Librarian. Boorstin's first challenge was the move to the new Madison Building, which took place between 1980 and 1982. The move released pressures on staff and shelf space, allowing Boorstin to focus on other areas of Library administration such as acquisitions and collections. Taking advantage of steady budgetary growth, from $116 million in 1975 to over $250 million by 1987, Boorstin actively participated in enhancing ties with scholars, authors, publishers, cultural leaders, and the business community. His active and prolific role changed the post of Librarian of Congress so that by the time he retired in 1987,
The New York Times called it "perhaps the leading intellectual public position in the nation".
President Ronald Reagan nominated
James H. Billington as the 13th Librarian of Congress in 1987, and the U.S. Senate unanimously confirmed the appointment.
 Under Billington's leadership, the Library doubled the size of its analog collections from 85.5 million items in 1987 to more than 160 million items in 2014. At the same time, it established new programs and employed new technologies to, "get the champagne out of the bottle." These included:
- American Memory created in 1990, which became The National Digital Library in 1994, providing free access online to digitized American history and culture resources with curatorial explanations for
THOMAS.gov website launched in 1994 to provide free public access to U.S. federal legislative information with ongoing updates; and CONGRESS.gov website to provide a state-of-the-art framework for both Congress and the public in 2012;
- The National Book Festival, founded in 2000 with
Laura Bush, has brought over 1000 authors and a million guests to the National Mall and the Washington Convention Center to celebrate reading. With a major gift from
David Rubenstein in 2013, the Library also established the Library of Congress Literacy Awards to recognize and support achievements in improving literacy in the U.S. and abroad;
- The Kluge Center, started with a grant of $60 million from John W. Kluge in 2000 to bring scholars and researchers from around the world to use Library resources and to interact with policymakers and the public. It hosts public lectures and scholarly events, provides endowed Kluge fellowships, and awards The Kluge Prize for the Study of Humanity (now worth $1.5 million), the first Nobel-level international prize for lifetime achievement in the humanities and social sciences (subjects not included in the Nobel awards);
- Open World Leadership Center, established in 2000, administered 23,000 professional exchanges for emerging post-Soviet leaders in Russia, Ukraine and the other successor states of the former USSR by 2015. Open World began as a Library of Congress project, and later became an independent agency in the legislative branch.
- The Veterans History Project, congressionally mandated in 2000 to collect, preserve, and make accessible the personal accounts of American war veterans from WWI to the present day;
- The National Audio-Visual Conservation Center, which opened in 2007 at a 45-acre site in Culpeper, Virginia with the largest private gift ever made to the Library (more than $150 million by the Packard Humanities Institute) and $82.1 million additional support from Congress. In 1988, The Library also established the National Film Preservation Board, a congressionally mandated National Film Preservation Board to select American films annually for preservation and inclusion in the new National Registry. The Librarian named 650 films to the Registry by 2015;
- The Gershwin Prize for Popular Song,
 launched in 2007 to honor the work of an artist whose career reflects lifetime achievement in song composition. Winners have included
Burt Bacharach and
Billy Joel, and just-named
Willie Nelson for November 2015. The Library also launched the
Living Legend Awards in 2000 to honor artists, activists, filmmakers, and others who have contributed to America's diverse cultural, scientific, and social heritage;
- The Fiction Prize (now the
Library of Congress Prize for American Fiction) started in 2008 to recognize distinguished lifetime achievement in the writing of fiction.
- The World Digital Library, established in association with UNESCO and 181 partners in 81 countries in 2009, to make online copies of professionally curated primary materials of the world's varied cultures freely available in multiple languages.
- National Jukebox launched in 2011 to provide streaming free online access to more than 10,000 out-of-print music and spoken word recordings.
- BARD in 2013, digital talking books mobile app for Braille and Audio Reading Downloads in partnership with the Library's National Library Service for the blind and physically handicapped, that enables free downloads of audio and
Braille books to mobile devices via the
Apple App Store.
During Billington's tenure as the 13th Librarian of Congress, the Library acquired Lafayette's previously inaccessible papers in 1996 from a castle at La Grange, France; and the only copy of the 1507
Waldseemüller world map ("America's birth certificate") in 2003 for permanent display in the Library's Thomas Jefferson Building. Using privately raised funds, the Library of Congress reconstructed Thomas Jefferson's original library, which was placed on permanent display in the Jefferson building in 2008.
 Billington also enlarged and technologically enhanced public spaces of the Jefferson Building into a national exhibition venue, and hosted over 100 exhibitions.
 These included exhibits on the
Vatican Library and the
Bibliothèque Nationale de France, several on the Civil War and Lincoln, on African-American culture, on Religion and the founding of the American Republic, the Early Americas (the Kislak Collection became a permanent display), on the global celebration commemorating the 800th anniversary of
Magna Carta, and on early American printing featuring the Rubenstein
Bay Psalm Book. Onsite access to the Library of Congress was also increased when Billington advocated successfully for an underground connection between the U.S. Capitol Visitors Center and the Library in 2008 to increase congressional usage and public tours of the Library's Thomas Jefferson Building.
Under Billington, the Library launched a
mass deacidification program in 2001, which has extended the lifespan of almost 4 million volumes and 12 million manuscript sheets; and new collection storage modules at Fort Meade, the first opening in 2002, to preserve and make accessible more than 4 million items from the Library's analog collections. Billington established the Library Collections Security Oversight Committee in 1992 to improve protection of collections, and also the Library of Congress Congressional Caucus in 2008 to draw attention to the Library's curators and collections. He created the Library's first Young Readers Center in the Jefferson Building in 2009, and the first large-scale summer intern (Junior Fellows) program for university students in 1991.
 Under Billington, the Library also sponsored the Gateway to Knowledge in 2010-2011, a mobile exhibition to 90 sites covering all states east of the Mississippi in a specially designed 18-wheel truck, increasing public access to Library collections off-site, particularly for rural populations.
Billington raised more than half a billion dollars of private support to supplement Congressional appropriations for Library collections, programs, and digital outreach. These private funds helped the Library to continue its growth and outreach in the face of a 30% decrease in staffing caused mainly by legislative appropriations cutbacks. He created the Library's first development office for private fundraising in 1987, and, in 1990, established the James Madison Council, the Library's first national private sector donor-support group. In 1987, Billington also asked the GAO to conduct the first Library-wide audit, and he created the first Office of the Inspector General at the Library to provide regular independent review of library operations. This precedent led to regular annual financial audits, leading to unmodified ("clean") opinions from 1995 onwards.
In April 2010, it announced plans to archive all public communication on Twitter, including all communication since Twitter's launch in March 2006.
 As of 2015 , the Twitter archive remains unfinished.
When Billington announced his plans to retire in 2015, commentator George Weigel described the Library of Congress as "one of the last refuges in Washington of serious bipartisanship and calm, considered conversation," and "one of the world's greatest cultural centers."
Carla Hayden was sworn in as the 14th Librarian of Congress on September 14, 2016, to become the first woman and first African-American to hold the position.