Washington, D.C. in the context of Navy Yard, Washington, D.C.

A tradition is a system of beliefs or behaviors (folk custom) passed down within a group of people or society with symbolic meaning or special significance with origins in the past. A component of cultural expressions and folklore, common examples include holidays or impractical but socially meaningful clothes (like lawyers' wigs or military officers' spurs), but the idea has also been applied to social norms and behaviors such as greetings, etc. Traditions can persist and evolve for thousands of years— the word tradition itself derives from the Latin word tradere literally meaning to transmit, to hand over, to give for safekeeping. While it is reportedly assumed that traditions have an ancient history, many traditions have been invented on purpose, whether it be political or cultural, over short periods of time. Various academic disciplines also use the word in a variety of ways.

The phrase "according to tradition" or "by tradition" usually means that what follows is known only through oral tradition and is not supported (and might even be refuted) by solid evidence. Here, "tradition" describes the source or nature of the information. For example, "According to tradition, Homer was born on Chios, but many other places have historically claimed him as theirs." This tradition may never be proven or disproved. Another example is, "King Arthur, according to history, a true British king, has inspired many well loved stories." Whether the claims are supported by evidence or not does not reduce their value as cultural history and literature.

The Pentagon is the headquarters building of the United States Department of Defense, in Arlington County, Virginia, across the Potomac River from Washington, D.C. The building was constructed on an accelerated schedule during World War II. As a symbol of the U.S. military, the phrase The Pentagon is often used as a metonym for the Department of Defense and its leadership.

The building was designed by American architect George Bergstrom and built by contractor John McShain. Ground was broken on 11 September 1941, and the building was dedicated on 15 January 1943. General Brehon Somervell provided the major impetus to gain Congressional approval for the project. Colonel Leslie Groves was responsible for overseeing the project for the U.S. Army Corps of Engineers, which supervised it.

The United States Department of Defense (DoD), also referred to as the Department of War (DoW), is an executive department of the U.S. federal government charged with coordinating and supervising the U.S. Armed Forces—the Army, Navy, Marines, Air Force, Space Force, and, for some purposes, the Coast Guard—and related functions and agencies. Headquartered at the Pentagon in Arlington County, Virginia, just outside Washington, D.C., the stated mission of the Department of Defense is "to provide the military forces needed to deter war and ensure our nation's security".

The Department of Defense is headed by the secretary of defense, a cabinet-level head who reports directly to the president of the United States. The president is commander-in-chief of the U.S. armed forces. Beneath the Department of Defense are three subordinate military departments: the Department of the Army, the Department of the Navy, and the Department of the Air Force. In addition, four national intelligence services are subordinate to the Department of Defense: the Defense Intelligence Agency, National Security Agency (NSA), National Geospatial-Intelligence Agency, and National Reconnaissance Office.

The National Geographic Society, headquartered in Washington, D.C., United States, is one of the largest nonprofit scientific and educational organizations in the world.

Founded in 1888, its interests include geography, archaeology, natural science, the promotion of environmental and historical conservation, and the study of world culture and history. The National Geographic Society's logo is a yellow portrait frame—rectangular in shape—which appears on the margins surrounding the front covers of its magazines and as its television channel logo. Through National Geographic Partners (a joint venture with The Walt Disney Company), the Society operates the magazine, TV channels, a website, worldwide events, and other media operations.

A think tank, or public policy institute, is an organization that performs research and advocacy concerning topics such as social policy, political strategy, economics, military, technology, and culture. Most think tanks are non-governmental organizations, but some are semi-autonomous agencies within a government, and some are associated with particular political parties, businesses, or the military. Think tanks are often funded by individual donations, with many also accepting government grants.

Think tanks publish articles and studies, and sometimes draft legislation on particular matters of policy or society. This information is then used by governments, businesses, media organizations, social movements, or other interest groups. Think tanks range from those associated with highly academic or scholarly activities to those that are overtly ideological and pushing for particular policies, with a wide range among them in terms of the quality of their research. Later generations of think tanks have tended to be more ideologically oriented.

The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 states and a federal capital district, Washington, D.C. The 48 contiguous states border Canada to the north and Mexico to the south, with the semi-exclave of Alaska in the northwest and the archipelago of Hawaii in the Pacific Ocean. The United States also asserts sovereignty over five major island territories and various uninhabited islands in Oceania and the Caribbean. It is a megadiverse country, with the world's third-largest land area and third-largest population, exceeding 340 million.

Paleo-Indians first migrated from North Asia to North America over 12,000 years ago, and formed various civilizations. Spanish colonization established Spanish Florida in 1513, the first European colony in what is now the continental United States. British colonization followed with the 1607 settlement of Virginia, the first of the Thirteen Colonies. Enslavement of Africans was practiced in all colonies by 1770 and supplied most of the labor for the Southern Colonies' plantation economy. Clashes with the British Crown over taxation and lack of parliamentary representation sparked the American Revolution, leading to the Declaration of Independence on July 4, 1776. Victory in the 1775–1783 Revolutionary War brought international recognition of U.S. sovereignty and fueled westward expansion, dispossessing native inhabitants. As more states were admitted, a North–South division over slavery led the Confederate States of America to attempt secession and fight the Union in the 1861–1865 American Civil War. With the United States' victory and reunification, slavery was abolished nationally. By 1900, the country had established itself as a great power, a status solidified after its involvement in World War I. Following Japan's attack on Pearl Harbor in 1941, the U.S. entered World War II. Its aftermath left the U.S. and the Soviet Union as rival superpowers, competing for ideological dominance and international influence during the Cold War. The Soviet Union's collapse in 1991 ended the Cold War, leaving the U.S. as the world's sole superpower.

The International Monetary Fund (IMF) is an international financial institution and a specialized agency of the United Nations, headquartered in Washington, D.C. It consists of 191 member countries, and its stated mission is "working to foster global monetary cooperation, secure financial stability, facilitate international trade, promote high employment and sustainable economic growth, and reduce poverty around the world." The IMF acts as a lender of last resort to its members experiencing actual or potential balance of payments crises.

Established in July 1944 at the Bretton Woods Conference based on the ideas of Harry Dexter White and John Maynard Keynes, the IMF came into formal existence in 1945 with 29 member countries and the goal of reconstructing the international monetary system. For its first three decades, the IMF oversaw the Bretton Woods system of fixed exchange rate arrangements. Following the collapse of this system in 1971, the Fund's role shifted to managing balance-of-payments difficulties and international financial crises, becoming a key institution in the era of globalization.

The World Bank Group (WBG) is a family of five international organizations that make leveraged loans to developing countries. It is the largest and best-known development bank in the world and an observer at the United Nations Development Group. The bank is headquartered in Washington, D.C., in the United States. It provided around $98.83 billion in loans and assistance to "developing" and transition countries in the 2021 fiscal year. The bank's stated mission is to achieve the twin goals of ending extreme poverty and building shared prosperity. Total lending as of 2015 for the last 10 years through Development Policy Financing was approximately $117 billion. Its five organizations have been established over time:

• International Bank for Reconstruction and Development (IBRD), 1944
• International Development Association (IDA), 1960
• International Finance Corporation (IFC), 1956
• International Centre for Settlement of Investment Disputes (ICSID), 1965
• Multilateral Investment Guarantee Agency (MIGA), 1988

The first two are sometimes collectively referred to as the World Bank. They provide loans and grants to the governments of low- and middle-income countries for the purpose of pursuing economic development. These activities include fields such as human development (e.g. education, health), agriculture and rural development (e.g. irrigation and rural services), environmental protection (e.g. pollution reduction, establishing and enforcing regulations), infrastructure (e.g. roads, urban regeneration, and electricity), large industrial construction projects, and governance (e.g. anti-corruption, legal institutions development). The IBRD and IDA provide loans at preferential rates to member countries, as well as grants to the poorest countries. Loans or grants for specific projects are often linked to wider policy changes in the sector or the country's economy as a whole. For example, a loan to improve coastal environmental management may be linked to the development of new environmental institutions at national and local levels and the implementation of new regulations to limit pollution. Furthermore, the World Bank Group is recognized as a leading funder of climate investments in developing countries.

The Thomas Jefferson Building, also known as the Main Library, is the oldest of the Library of Congress buildings in Washington, D.C. Built between 1890 and 1897, it was initially known as the Library of Congress Building. In 1980, the building was named in honor of Thomas Jefferson (1743–1826), a Founding Father, the principal author of the Declaration of Independence, and the third U.S. president. In 1815, the purchase of Jefferson's book collection formed a core foundation for the library's collection.

The building is located on First Street, S.E. between Independence Avenue and East Capitol Street in the federal national capital city of Washington, D.C., across from the United States Capitol on Capitol Hill. It is adjacent to the library's additional buildings in the Library of Congress complex, the John Adams Building (built in the 1930s) across Second Street, and the James Madison Memorial Building (built in the 1970s) across Independence Avenue to the south.

The Pew Research Center (also simply known as Pew) is a nonpartisan American think tank based in Washington, D.C. It provides information on social issues, public opinion, and demographic trends shaping the United States and the world. It also conducts public opinion polling, demographic research, random sample survey research, and panel based surveys, media content analysis, and other empirical social science research.

The Pew Research Center states it does not take policy stances. It is a subsidiary of the Pew Charitable Trusts and a charter member of the American Association of Public Opinion Research's Transparency Initiative.

Inter-city rail services are express trains that run services that connect cities over longer distances than commuter or regional trains. They include rail services that are neither short-distance commuter rail trains within one city area nor slow regional rail trains stopping at all stations and covering local journeys only. An inter-city train is typically an express train with limited stops and comfortable carriages to serve long-distance travel.

Inter-city rail sometimes provides international services. This is most prevalent in Europe because of the proximity of its 50 countries to a 10,180,000-square-kilometre (3,930,000-square-mile) area. Eurostar and EuroCity are examples. In many European countries, the word InterCity or Inter-City is an official brand name for a network of regular-interval and relatively long-distance train services that meet certain criteria of speed and comfort. That use of the term appeared in the United Kingdom in the 1960s and has been widely imitated.

In the United States, a county or county equivalent is an administrative subdivision of a state or territory, typically with defined geographic boundaries and some level of governmental authority. The term "county" is used in 48 states, while Louisiana and Alaska have functionally equivalent subdivisions called parishes and boroughs, respectively. Counties and other local governments exist as a matter of U.S. state law, so the specific governmental powers of counties may vary widely between the states, with many providing some level of services to civil townships, municipalities, and unincorporated areas. Certain municipalities are in multiple counties. Some municipalities have been consolidated with their county government to form consolidated city-counties or have been legally separated from counties altogether to form independent cities. Conversely, counties in Connecticut and Rhode Island, eight of Massachusetts's 14 counties, and Alaska's Unorganized Borough have no government power, existing only as geographic distinctions.

The United States Census Bureau uses the term "county equivalent" to describe places that are comparable to counties, but called by different names. Louisiana parishes, the organized boroughs of Alaska, independent cities, and the District of Columbia are equivalent to counties for administrative purposes. Alaska's Unorganized Borough is further divided into 11 census areas that are statistically equivalent to counties. In 2024, the U.S. Census Bureau began to also recognize Connecticut's councils of governments, which took over some of the regional powers from the state's former county governments, as county equivalents.

The United States of America is a federal republic consisting of 50 states, a federal district (Washington, D.C., the capital city of the United States), five major territories, and minor islands. Both the states and the United States as a whole are each sovereign jurisdictions. The Tenth Amendment to the United States Constitution allows states to exercise all powers of government not delegated to the federal government. Each state has its own constitution and government. All states and their residents are represented in the federal Congress, a bicameral legislature consisting of the Senate and the House of Representatives. Each state elects two senators, while representatives are distributed among the states in proportion to the most recent constitutionally mandated decennial census.

Each state is entitled to select a number of electors to vote in the Electoral College, the body that elects the president of the United States, equal to the total of representatives and senators in Congress from that state. The federal district does not have representatives in the Senate, but has a non-voting delegate in the House, and it is entitled to electors in the Electoral College. Congress can admit more states, but it cannot create a new state from territory of an existing state or merge two or more states into one without the consent of all states involved. Each new state is admitted on an equal footing with the existing states.

The Treaty of Peace between the United States of America and the Kingdom of Spain, commonly known as the Treaty of Paris of 1898, was signed by Spain and the United States on December 10, 1898, and marked the official end of the Spanish–American War. Under it, Spain relinquished all claim of sovereignty over the West Indies archipelagos and islands of Cuba and Puerto Rico in the Caribbean, the Western Pacific island of Guam in the Marianas archipelago in Micronesia, and the Western Pacific archipelago of the Philippines in Southeast Asia to the United States. The cession of the Philippines involved a compensation of $20 million from the United States to Spain.

The treaty was preceded by the Spanish-American War armistice, a preliminary peace agreement signed on August 12, 1898 in Washington, DC. The armistice formally stopped the active hostilities between Spain and the United States, requiring Spain to cede Cuba, Puerto Rico, and Guam to the United States, and to agree to the American occupation of Manila in the Philippines. The treaty came into effect on April 11, 1899, when the documents of ratification were exchanged. It was the first treaty negotiated between the two governments since the 1819 Adams–Onís Treaty.

The National Aeronautics and Space Administration (NASA /ˈnæsə/) is an independent agency of the US federal government responsible for the United States' civil space program and for research in aeronautics and space exploration. Headquartered in Washington, D.C., NASA operates ten field centers across the United States and is organized into mission directorates for Science, Space Operations, Exploration Systems Development, Space Technology, Aeronautics Research, and Mission Support. Established in 1958, NASA succeeded the National Advisory Committee for Aeronautics (NACA) to give the American space development effort a distinct civilian orientation, emphasizing peaceful applications in space science. It has since led most of America's space exploration programs, including Project Mercury, Project Gemini, the 1968–1972 Apollo program missions, the Skylab space station, and the Space Shuttle.

The agency maintains major ground and communications infrastructure including the Deep Space Network and the Near Space Network. NASA's science division is focused on better understanding Earth through the Earth Observing System; advancing heliophysics through the efforts of the Science Mission Directorate's Heliophysics Research Program; exploring bodies throughout the Solar System with advanced robotic spacecraft such as New Horizons and planetary rovers such as Perseverance; and researching astrophysics topics, such as the Big Bang, through the James Webb Space Telescope, the four Great Observatories (including the Hubble Space Telescope), and associated programs. The Launch Services Program oversees launch operations for its uncrewed launches.

Maryland (US: /ˈmɛrɪlənd/ MERR-il-ənd) is a state in the Mid-Atlantic and South Atlantic region of the United States. It borders the states of Virginia to its south, West Virginia to its west, Pennsylvania to its north, and Delaware to its east, as well as with the Atlantic Ocean to its east, and the national capital and federal district of Washington, D.C. to the southwest. With a total area of 12,407 square miles (32,130 km), Maryland is the ninth-smallest state by land area, and its population of 6,177,224 ranks it the 18th-most populous state and the fifth-most densely populated. Maryland's capital city is Annapolis, and the state's most populous city is Baltimore.

Maryland's coastline was first explored by Europeans in the 16th century. Prior to that, it was inhabited by several Native American tribes, mostly the Algonquian peoples. One of the original Thirteen Colonies, the Province of Maryland was founded in 1634 by George Calvert, 1st Baron Baltimore, a Catholic convert who sought to provide a religious haven for Catholics persecuted in England. In 1632, Charles I of England granted Lord Baltimore a colonial charter, naming the colony after his wife, Henrietta Maria. In 1649, the Maryland General Assembly passed an Act Concerning Religion, which enshrined the principle of toleration. Religious strife was common in Maryland's early years, and Catholics remained a minority, albeit in greater numbers than in any other English colony.

Arlington County, or simply Arlington, is a county in the U.S. state of Virginia. The county, which is located in the Washington metropolitan area and the broader Northern Virginia region, is positioned directly across from Washington, D.C., the national capital, on the southwestern bank of the Potomac River. The smallest self-governing county in the United States by area, Arlington County has both suburban and urbanized districts. Its urbanized districts are located in proximity to several Washington Metro stations and lines. Its seat of government is located in the Court House neighborhood, which hosts many of its administrative offices and county courthouse.

Originally part of the Nacotchtank tribe's territory prior to the establishment of the Colony of Virginia in 1606, English colonists began settling in Arlington by the 1670s; the area was eventually designated as part of Fairfax County in 1742. The colonial-era economy was mostly based in tobacco agriculture operated with enslaved labor and indentured servants on large plantations. Following the end of the Revolutionary War, Arlington's planters and yeoman farmers transitioned to other crops. Virginia ceded present-day Arlington to help form the District of Columbia, and from 1801 the area was known as Alexandria County; it was eventually retroceded back to Virginia in 1847 as a result of pressure from Alexandria, which was the county's primary commercial center.