How many national libraries does the US have?
There is no single law that defines the term, so the honest answer is: it depends who you ask. Three are classically recognized — the Library of Congress, the National Library of Medicine, and the National Agricultural Library. Add the National Library of Education and you get four, the count most relevant to schools. By the broadest reckoning there are five, adding the National Transportation Library. Each is the flagship national collection for its field, and most are federal research libraries rather than places the public walks into. Here is what each one is, and what it offers students and teachers.
The largest library in the world; serves Congress and the public.
The world’s largest biomedical library (NIH).
A world-leading agriculture and nutrition collection (USDA).
The federal government’s education library (Dept. of Education).
Library of Congress
The Library of Congress in Washington, DC is the largest library in the world and the research arm of the US Congress. For students and teachers its value is online: enormous free digital collections of photographs, maps, manuscripts, historic newspapers, audio, and film, a dedicated teachers section with primary-source classroom materials, and a “Free to Use and Reuse” program of public-domain images. It is also where national treasures like rough drafts of the Declaration of Independence are held.
National Library of Medicine
Part of the National Institutes of Health, the NLM is the world’s largest biomedical library. Its free public tools include MedlinePlus (plain-language health information for families) and PubMed (research literature). For high-school biology, health, and science-fair work, these are authoritative, free sources.
National Agricultural Library
Run by the US Department of Agriculture, the NAL holds a world-leading collection on agriculture, food, and nutrition. Public resources include Nutrition.gov and kid-friendly recipes, open agricultural datasets, and research databases, useful for science, health, and family- and consumer-science classes.
National Library of Education
Housed in the US Department of Education’s Institute of Education Sciences, the National Library of Education is the federal government’s primary education library. It holds historical federal education reports and a large collection of classroom textbooks, and it connects to ERIC (the Education Resources Information Center) and the What Works Clearinghouse, where teachers and researchers find evidence on what improves learning.
National Transportation Library
Part of the US Department of Transportation’s Bureau of Transportation Statistics, the NTL is a fully digital library of transportation research and data. It is the one most often left off the list, which is why the count ranges from three to five.
National libraries vs. your local library
National libraries are specialized federal collections. With the exception of the Library of Congress, they mainly serve researchers and are not where you borrow a novel. For everyday borrowing, databases, and homework help, the library that serves you is your public library and your state library. See what yours offers in the state library guides.