| A 52.1 | National Advisory Loan Committee (1931) |
| NAS 1.1 | National Aeronautics and Space Administration (1958- ) |
| PrEx 5.1 | National Aeronautics and Space Council (1961- 1973) |
| A 17.1 | National Agricultural Library (1962-1978, 1981- ) |
| A 92.1 | National Agricultural Statistics Service (1986- ) |
| SI 9.1 | National Air and Space Museum (1967- ) |
| HE 20.1301 | National Air Pollution Control Administration (1970-?) |
| AE 1.1 | National Archives (1934-1949) |
| AE 1.101 | National Archives and Records Administration (1985- ) |
| GS 4.1 | National Archives and Records Service (1949-1985) |
| I 73.2 | National Biological Service (1993-1996) |
| I 34.1 | National Bituminous Coal Commission (1935-1939) |
| W 82.1 | National Board for Promotion of Rifle Practice (1914-1922) |
| T 29.1 | National Board of Health (1879-1886) |
| T 41.1 | National Bureau of Standards (1901-1903) |
| HE 20.3151 | National Cancer Institute (1970- ) |
| NC 1.1 | National Capital Park and Planning Commission (1926-1952) |
| NC 2.1 | National Capital Planning Commission (1952- ) |
| NC 3.1 | National Capital Regional Planning Council (1952-1966) |
| HE 20.7601 | National Center for Chronic Disease Prevention and |
| Health Promotion (1984- ) | |
| HE 20.7252 | National Center for Complementary and Alternative |
| Medicine (1998- ) | |
| ED 1.601/2 | National Center for Education Evaluation and Regional Assistance |
| ED 1.702 | National Center for Education Research |
| ED 1.101 | National Center for Education Statistics (1979- ) |
| HE 19.301 | National Center for Educational Statistics (1972-1979) |
| HE 20.7501 | National Center for Environmental Health (1984- ) |
| HE 20.2909 | National Center for Family Planning Service (1972- 1973) |
| HE 20.201 | National Center for Health Care Technology (1978-1982) |
| HE 20.2101 | National Center for Health Services Research and |
| Development (1970- 1973) | |
| HE 20.2201 | National Center for Health Statistics (1970-1973) |
| HE 20.6201 | National Center for Health Statistics (1973- ) |
| HE 20.7301 | National Center for HIV/AIDS, Viral Hepatitis, STD, and |
| TB Prevention (1973- ) | |
| HE 20.7962 | National Center for Immunization and Respiratory |
| Diseases (1993- ) | |
| HE 20.7801 | National Center for Infectious Diseases (1984-2008) |
| HE 20.7952 | National Center for Injury Prevention and Control (1992- ) |
| AA 3.1 | National Center for Service Learning (1980-1994) |
| FS 17.601 | National Center for Social Statistics (1968-1969) |
| HE 17.601 | National Center for Social Statistics (1970- ?) |
| C 55.190 | National Centers for Environmental Prediction |
| PrEx 13.1 | National Clearinghouse for Drug Abuse Information (1970- 1973) |
| HE 23.3101 | National Clearinghouse on Aging (1977-?) |
| C 55.280 | National Climatic Data Center (1970- ) |
| PrEx 11.1 | National Council of the Arts (1964-1965) |
| PrEx 12.1 | National Council on Marine Resources and Engineering |
| Development (1966- 1971) | |
| NCU 1.1 | National Credit Union Administration (1970- ) |
| D 5.401 | National Defense University (1977- ) |
| C 55.501 | National Earth Satellite Service (1971-1980) |
| C 55.690 | National Earthquake Information Center (1966-1973) |
| NF 2.1 | National Endowment for the Arts (1965- ) |
| NF 3.1 | National Endowment for the Humanities (1965- ) |
| E 12.1 | National Energy Technology Laboratory (1999- ) |
| ES 6.1 | National Enforcement Commission (1952-1953) |
| C 55.201 | National Environmental Satellite, Data, and Information |
| Service (1970- ) | |
| HE 20.3751 | National Eye Institute (1970- ) |
| NF 1.1 | National Foundation on the Arts and the Humanities (1965- ) |
| SI 8.1 | National Gallery of Art (1937- ) |
| D 5.301 | National Geospatial-Intelligence Agency (1972- ) |
| W 70.1 | National Guard Bureau (1933-1947) |
| M 114.1 | National Guard Bureau (1947-1949) |
| D 112.1 | National Guard Bureau (1949-1958) |
| D 12.1 | National Guard Bureau (1958- ) |
| HE 20.3201 | National Heart, Lung, and Blood Institute (1975- ) |
| TD 2.201 | National Highway Safety Bureau (1966-1970) |
| TD 8.1 | National Highway Traffic Safety Administration (1970- ) |
| NH 1.1 | National Home for Disabled Volunteer Soldiers (1866-1930) |
| NHA 1.1 | National Housing Agency (1942-1947) |
| HE 20.2801 | National Institute for Occupational Safety and Health (1971- 1974) |
| HE 20.7101 | National Institute for Occupational Safety and Health (1974- ) |
| HE 20.8301 | National Institute of Alcohol Abuse and Alcoholism (1973- ) |
| HE 20.3251 | National Institute of Allergy and Infectious Diseases (1970- ) |
| HE 20.3902 | National Institute of Arthritis and Musculoskeletal and |
| Skin Diseases (1984- ) | |
| HE 20.3351 | National Institute of Child Health and Human Development (1970- ) |
| HE 20.3401 | National Institute of Dental and Craniofacial Research (1970- ) |
| HE 20.3301 | National Institute of Diabetes and Digestive and Kidney |
| Diseases (1985- ) |
| HE 18.1 | National Institute of Education (1972-1975) |
| HE 19.201 | National Institute of Education (1975-1979) |
| HE 20.3551 | National Institute of Environmental Health Sciences (1970- ) |
| A 94.1 | National Institute of Food and Agriculture (1961-1978, 1981- ) |
| HE 20.3451 | National Institute of General Medical Sciences (1970- ) |
| J 28.1 | National Institute of Justice (1979- ) |
| HE 20.2401 | National Institute of Mental Health (1970-1973) |
| HE 20.3801 | National Institute of Mental Health (1970-1974) |
| HE 20.8101 | National Institute of Mental Health (1973- ) |
| HE 20.3501 | National Institute of Neurological Disorders and Stroke (1975- ) |
| C 13.1 | National Institute of Standards and Technology (1934- ) |
| HE 20.3851 | National Institute on Aging (1976- ) |
| HE 20.3652 | National Institute on Deafness and Other Communication Disorders (1988- ) |
| HE 20.8201 | National Institute on Drug Abuse (1973-1992) |
| HE 20.3952 | National Institute on Drug Abuse (1992- ) |
| HE 20.3001 | National Institutes of Health (1970- ) |
| C 32.1 | National Inventors Council (1940-1963) |
| LR 1.1 | National Labor Relations Board (1935- ) |
| FS 2.201 | National Library of Medicine (1956-1969) |
| HE 20.3601 | National Library of Medicine (1970- ) |
| LC 19.1 | National Library Service for the Blind and Physically |
| Handicapped (1931- ) | |
| C 55.301 | National Marine Fisheries Service (1970- ) |
| NMB 1.1 | National Mediation Board (1934- ) |
| M 1.1 | National Military Establishment (1947-1949) |
| SI 14.2 | National Museum of African Art (1979- ) |
| SI 3.1 | National Museum of American History/National Museum of Natural History (1980- ) |
| SI 15.2 | National Museum of the American Indian |
| E 11.2 | National Nuclear Security Administration (2000- ) |
| C 55.401 | National Ocean Service (1970- ) |
| C 55.1 | National Oceanic and Atmospheric Administration (1970- ) |
| C 55.290 | National Oceanographic Data Center (1970- ) |
| FS 2.101 | National Office of Vital Statistics (1946-1969) |
| I 29.1 | National Park Service (1916- ) |
| SI 11.1 | National Portrait Gallery (1961- ) |
| C 40.1 | National Production Authority (1950-1953) |
| RA 1.1 | National Railroad Adjustment Board (1934- ) |
| RA 3.1 | National Railroad Adjustment Board Third Division (1934-?) |
| E 9.2 | National Renewable Energy Laboratory (1977- ) |
| NA 2.1 | National Research Council (1916- ) |
| PR 32.301 | National Resources Planning Board (1939-1943) |
| NS 1.1 | National Science Foundation (1950- ) |
| Pr 33.601 | National Security Council (1949-1953) |
| Pr 33.701 | National Security Resources Board (1949-1953) |
| SI 5.1 | National Society of the Daughters of the American |
| Revolution (1896-1948) | |
| C 51.1 | National Technical Information Service (1970- ) |
| C 60.1 | National Telecommunications and Information |
| Administration (1978- ) | |
| J 8.1 | National Training School for Boys (1908-1939) |
| J 9.1 | National Training School for Girls (1912-1926) |
| TD 1.101 | National Transportation Safety Board (1966- ) |
| L 10.1 | National War Labor Board (1918-1919) |
| Pr 32.5101 | National War Labor Board (1942-1945) |
| C 55.101 | National Weather Service (1970- ) |
| FS 6.1 | National Youth Administration (1939-1942) |
| A 57.1 | Natural Resources Conservation Service (1935-1942, 1945- ) |
| N 11.1 | Nautical Almanac Office (1849-1947) |
| D 208.101 | Naval Academy (1845- ) |
| N 12.1/1 | Naval Academy (1845-1947) |
| M 206.101 | Naval Academy (1947-1949) |
| D 202.1 | Naval Air Systems Command (1966- ) |
| N 22.1 | Naval Communications Service (1912-1947) |
| D 221.1 | Naval Data Automation Command (1980-1992) |
| D 207.402 | Naval Doctrine Command (1993-1999) |
| D 207.201 | Naval Education and Training Command (1972- ) |
| D 209.1 | Naval Facilities Engineering Command (1966- ) |
| D 221.2 | Naval History and Heritage Command |
| D 218.1 | Naval Meteorology and Oceanography Command (1967- ) |
| N 14.1/1 | Naval Observatory (1842-1947) |
| M 212.1 | Naval Observatory (1947-1949) |
| D 213.1 | Naval Observatory (1949- ) |
| D 210.101 | Naval Ocean Research and Development Activity |
| D 203.1 | Naval Oceanographic Service (1962-2000) |
| D 215.1 | Naval Ordnance Systems Command (1966-1974) |
| N 16.1 | Naval Records and Library Office (1895-1947) |
| N 25.1 | Naval Reserve Force Division (1915-1918) |
| D 211.1 | Naval Sea Systems Command (1974- ) |
| D 212.1 | Naval Supply Systems Command (1966- ) |
| D 207.101 | Naval Technical Training Command (1971-?) |
| D 208.201 | Naval War College (1884- ) |
| N 15.1 | Naval War College (1884-1947) |
| M 206.201 | Naval War College (1947-1949) |
| D 220.1 | Naval Weather Service Command (1968-?) |
| HH 11.1 | New Communities Administration |
| D 9.1 | North Atlantic Treaty Organization (1949-?) |
| W 86.1 | Northeastern Department (1917-1920) |
| W 33.1 | Northern and Northwestern Lakes Survey (1841-1947) |
| W 62.1 | Northern Division (1904-1907) |
