The U.S. National Library of Medicine (NLM), operated by the U.S. federal government, is the world's largest medical research library. The collections of the National Library of Medicine include more than 3.5 million books, journals, technical reports, theses, pamphlets, photographs, manuscripts and audiovisual materials.
The NLM was established in 1836 as the library of the Army Surgeon General's Office. The Armed Forces Institute of Pathology and its Medical Museum were founded in 1862 as the Army Medical Museum. Throughout their history the Army Medical Library and the Army Medical Museum often shared quarters. From 1866 to 1887, they were housed in Ford's Theatre after production there was stopped following the assassination of President Abraham Lincoln.
In 1936, the Library collection was transferred from the control of the Department of Defense to the Public Health Service of the Department of Health, Education and Welfare and renamed the National Library of Medicine. The Library moved to its current quarters in Bethesda, Maryland, on the campus of the National Institutes of Health in 1962.
The National Library of Medicine produces, many databases and indexes including, Index Medicus (1879-2004), MEDLINE (since 1971), MedlinePlus.gov (since 1998), and ClinicalTrials.gov (since 2002).