Washington, D.C. (commonly referred to as Washington; the District; or simply D.C.) is the capital of the United States founded on July 16, 1790. Washington (the city) covers the same area as (i.e. is coterminous with) the District of Columbia and they are considered to be the same entity. The District of Columbia is located on the banks of the Potomac River and bordered by the states of Virginia to the southwest and Maryland to the northwest, northeast, and southeast. Washington has a resident population of 588,292; however, the city's population rises to over one million people during the workweek due to commuters from the surrounding suburbs. The Washington Metropolitan Area has a total population of 5.3 million, the eighth-largest in the country.

Article One of the United States Constitution provides for a federal district, distinct from the states, to serve as the permanent national capital. The centers of all three branches of the Federal government of the United States are located in the District, as are many of the nation's monuments and museums. Washington, D.C. hosts 172 foreign embassies as well as the headquarters of the World Bank, the International Monetary Fund (IMF), the Organization of American States (OAS), the Inter-American Development Bank, and other national and international institutions, including trade unions and professional associations.

The United States Congress has supreme authority over Washington, D.C., which results in residents of the city having less self-governance than residents of the states. The District has a non-voting at-large Congressional delegate, but no senators. If Washington, D.C. were a state, it would rank last in area (behind Rhode Island), second to last in population (ahead of Wyoming), first in population density, 35th in gross state product, and first in percentage of African Americans, which would make Washington, D.C. a minority-majority state.

The history of Washington, D.C. is tied intrinsically to its role as the capital of the United States. The site along the Potomac River was chosen for the capital city by George Washington, and approved by the United States Congress in the 1790 Residence Act. The city came under attack during the War of 1812 in an episode known as the Burning of Washington. Upon return to the capital, numerous public buildings including the White House and United States Capitol Building needed to be rebuilt. The 1901 McMillan Plan helped restore and beautify the downtown core area, including establishing the National Mall, along with numerous monuments and museums.

Slavery was abolished throughout the District on April 16, 1862, though the city remained racially segregated until the 1950s. During the early 20th century, the U Street Corridor served as an important center for African American culture. After desegregation, racial tensions remained high in the city, and the assassination of Martin Luther King Jr. in 1968 sparked major riots. Following the riots, large sections of the city remained blighted areas. The Washington Metro opened in 1976, and gentrification in the late 1990s and 2000s allowed many neighborhoods to revitalize.

Throughout much of its history, Washington D.C. residents lacked representation in the Federal government. The Twenty-third Amendment to the United States Constitution, ratified in 1961, gave the District representation in the electoral college. The 1973 District of Columbia Home Rule Act provided the local government more control of affairs, including direct election of the city council and mayor. Because it is not a state, the District of Columbia still lacks voting rights in Congress.

Archaeological evidence indicates Native Americans settled in Washington, D.C. at least 4000 years ago, around the Anacostia River. Early European exploration of the region took place early in the 17th century, including explorations by Captain John Smith in 1608. At the time, Powhatans inhabited the Virginia side of the Potomac River, and Piscataway Indians (also known as Conoy) Algonquian people resided on the Maryland side. Native settlements within the present-day District of Columbia included Nacostines, at Anacostia, who were affiliated with the Conoy. Another village was located between Little Falls and Georgetown.

European settlers began arriving in the following decades, pushing the natives west, as the Virginia Colony expanded from the south and the Province of Maryland from the east. While the central portion of the current capital city was largely uninhabitable wetlands, two business and port towns evolved nearby, on opposite sides of the Potomac River. The town of Georgetown, generally coterminous with the modern neighborhood of that name, was first settled in 1706, and continuously settled after 1751. The Old Stone House, built in 1765, is located in Georgetown and is the oldest standing building in the city. The city of Alexandria, Virginia was established in 1749. Two smaller settlements existed in central areas of what would become the Federal District. Carrollsburg was located at Greenleaf's Point, along the Southwest Waterfront. Hamburgh was another settlement, located near the present day State Department headquarters in Foggy Bottom.

After the conclusion of the American Revolutionary War in 1783, the new federal government of the United States met in New York City and Philadelphia. Rivalry among the states to be home to the new capital led the 1787 Constitutional Convention to empower Congress in Article I, Section 8 of the new United States Constitution

To exercise exclusive Legislation in all Cases whatsoever, over such District (not exceeding ten miles square) as may, by Cession of particular States, and the acceptance of Congress, become the Seat of the Government of the United States.

A new federal district was to be established, governed by Congress which was not part of any state. A Southern site for the capital was agreed upon at a sit-down dinner between Thomas Jefferson and Alexander Hamilton. Jefferson agreed to support Hamilton's banking and federal bond plans that involved the Federal government assuming state debts in exchange for the choice of a Southern locale for the capital.

On December 23, 1788, the Maryland General Assembly passed an act, allowing it to cede land for the federal district. The Virginia General Assembly followed suit on December 3, 1789. The signing of the Residence Act on July 6, 1790 mandated that a site, not exceeding "ten miles square" (100 square miles), be located on the "River Potomac, at some place between the mouths of the Eastern Branch and Connogocheque" for the permanent seat of government. The Residence Act authorized the President of the United States to select the actual location of the site.

However, President George Washington wished to include the town of Alexandria, Virginia within a square federal district that would contain the full 100 square miles (259 km²) that the Residence Act had authorized. To accomplish this, the boundaries of the federal district would need to encompass an area on the Potomac that was downstream of the mouth of the Eastern Branch (now the Anacostia River) and was therefore not "between the mouths of the Eastern Branch and Connogocheque."

The U.S. Congress amended the Residence Act in 1791 to permit Alexandria's inclusion in the federal district. However, some members of Congress had recognized that Washington and his family owned property in and near Alexandria, which was just seven miles upstream from Mount Vernon, Washington's home and plantation. The amendment therefore contained a provision that prohibited the construction of federal office buildings on the Virginia side of the Potomac River.

The final site was just below the fall line of the Potomac—the farthest point upstream to which oceangoing boats could navigate. It included the ports of both Georgetown, Maryland and Alexandria, and was a key point for transferring goods, particularly tobacco, between oceangoing ships and land or riverine transports. However, the site was also accessible to foreign armed forces, as became apparent only two decades later, when British invaders set fire to the capital's federal buildings during the War of 1812.

Washington, who had long promoted the location of the nation's capital along the Potomac, may also have chosen the site for its natural scenery and its location near the center of the new nation. He certainly believed that the Potomac had the potential to be a great navigable waterway, for he had founded the Potowmack Company in 1785 to make navigability-increasing improvements (including several canals) to the river.

Land for the district was given to the federal government by the states of Virginia and Maryland. The pre-existing towns of Georgetown and Alexandria were included in the new district, with the remainder of the territory subdivided into Washington City and the County of Washington on the Maryland side of the Potomac (named after George Washington) and Alexandria County on the Virginia side.

The process of establishing the federal district faced further challenges, in form of strong objections from landowners such as David Burns who owned a large, 650 acre (263 hectares) tract of land in the heart of the district. On March 30, 1791, Burns and eighteen other key landowners relented and signed an agreement with Washington, where they would be compensated for any land taken for public use, half of remaining land would be distributed among the proprietors, and the other half to the public.

Pursuant to the Residence Act, President Washington appointed three commissioners (Thomas Johnson, Daniel Carroll, and David Stuart) in 1791 to supervise the planning, design and acquisition of property in the federal district and capital city.

The site sits on what was originally the main trading town of the Conoy Indians, and served as the home and headquarters of Chief Patawomeke. The section of Washington, D.C. called Anacostia is a Latinized version of the town's name: Naconchtanke.

Washington appointed Pierre Charles L'Enfant to devise a plan for the new city. L'Enfant designed the city's first layout, a grid centered on the United States Capitol, crossed by diagonal avenues later named after the states of the union. L'Enfant's plan was presented to George Washington on August 19, 1791. The intersections of these avenues with the north-south and east-west streets were carved into grand circles and plazas which would later honor notable Americans. L'Enfant laid out a wide "grand avenue," which he expected to travel on an east-west axis in the center of the area that the National Mall now occupies.

L'Enfant also designed a narrower avenue (Pennsylvania Avenue) which would connect the "Federal House" (Capitol) with the "President palace" (White House). In time, Pennsylvania Avenue developed into the capital city's present "grand avenue."

In September 1791, the three commissioners agreed to name the Federal District as "The Territory of Columbia," and the Federal city "The City of Washington."

During 1791 and 1792, Major Andrew Ellicott, with assistants including his brother, Joseph Ellicott, Isaac Briggs, George Fenwick, and an African-American assistant, Benjamin Banneker, surveyed the borders of the Territory of Columbia with Virginia and Maryland. They placed sandstone boundary markers at or near every mile point. Many of these still remain.

The cornerstone of the White House – the first new constructed building of the new capital – was laid on October 13, 1792. That was the day after the first celebrations of Columbus Day, marking the 300th anniversary of the explorer's first voyage to the New World. While surveying and construction were underway, both Congress and Presidents Washington and John Adams governed from other cities.

L'Enfant designed the grid only as far as Boundary Street (later to be called Florida Avenue), at the base of the fall line. In 1792, President Washington dismissed L'Enfant from federal service. Popular legend says that L'Enfant was fired because, when a house had needed to be removed for one of his avenues, he had lured the reluctant owner out of the house and then blew it up with explosives. In addition, L'Enfant had numerous conflicts with the three commissioners that Washington had appointed to supervise the design, survey and development of the federal district and capital city.

Following L'Enfant's dismissal, Washington and the commissioners appointed surveyor Andrew Ellicott to complete the planning and design of the capital city. To L'Enfant's dismay, Ellicott soon revised the city's plan, straightening Massachusetts Avenue, eliminating several plazas and streets and giving names to the streets. Unlike L'Enfant, Ellicott was able to have his own plan engraved, published and distributed. As a result, Ellicott's plan became the basis for the capital city's future development.

The city's grid pattern consists of numbered streets north-south and lettered streets running east-west. Curiously, however, there is no "J Street." Popular legend has it that this was due to L'Enfant's personal dislike of John Jay. The real reason was to prevent confusion that would result from the similarities of how the Roman letters "I" and "J" were written. Moreover, to eliminate the possible ambiguity between First Street and "I Street," the latter is conventionally written "Eye Street."

In 1800, the seat of government was finally moved to the new city, and on February 27, 1801, the district was formally placed under the jurisdiction of Congress.

The District of Columbia relied on Congress for support for capital improvements and economic development initiatives. However, Congress lacked loyalty to the city's residents and was reluctant to provide support.

During the War of 1812, President James Madison and the fledgling U.S. government were forced to flee the District. The expedition was carried out between August 19 and August 29, 1814, and was well organized and vigorously executed. On the 24th, the American militia, which had collected at Bladensburg, Maryland, to protect the capital, retreated from the Capital City before it could be destroyed.

On August 24, 1814, British forces burned the capital during the most notably destructive raid of the war. British forces burned the most important public buildings, including the Presidential Mansion, the U.S. Capitol, the Arsenal, the Navy Yard, the Treasury Building, the War Office, and the bridge across the Potomac.

The British, however, spared the Marine Barracks at 8th and I streets, SE. It is said they spared the Barracks out of respect for the Marines who fought at the Battle of Bladensburg.

Almost immediately after the "Federal City" was laid out north of the Potomac, some residents south of the Potomac in Alexandria County, D.C. began petitioning to be returned to Virginia's jurisdiction. Over time, a larger movement grew to separate Alexandria from the District for several reasons:

* Alexandria's economy had stagnated as competition with the port of Georgetown, D.C. had begun to favor the north side of the Potomac, where most members of Congress and local federal officials resided.
* The Alexandria Canal, which connected the Chesapeake and Ohio Canal to Alexandria, needed repairs, which the federal government was reluctant to fund.
* Alexandria's residents had lost representation and the right to vote at any level of government.
* Alexandria was a center for slave trading. There was increasing talk of abolition of slavery in the national capital. Alexandria's economy would suffer if slavery were outlawed in the District of Columbia.
* There was an active abolition movement in Virginia, and the pro-slavery forces held a slim majority in the Virginia General Assembly. (Eighteen years later, in the American Civil War, the most anti-slavery counties would secede from Virginia to form West Virginia.) If Alexandria and Alexandria County were retroceded to Virginia, they would provide two new pro-slavery representatives.

After a referendum, Alexandria County's citizens petitioned Congress and Virginia to return the area to Virginia. By an act of Congress on July 9, 1846, and with the approval of the Virginia General Assembly, the area south of the Potomac (39 square miles [101 km²]) was returned, or "retroceded," to Virginia effective in 1847.

The retroceded land was then known as Alexandria County, Virginia, and now includes a portion of the independent city of Alexandria and all of Arlington County, the successor to Alexandria County. A large portion of the retroceded land near the river was an estate of George Washington Parke Custis, who had supported the retrocession and helped develop the charter in the Virginia General Assembly for the County of Alexandria, Virginia. The estate (Arlington Plantation) would be passed on to his daughter (the wife of Robert E. Lee), and would eventually become Arlington National Cemetery.

Washington remained a small city of a few thousand residents, virtually deserted during the torrid summertime, until the outbreak of the U.S. Civil War in 1861. President Abraham Lincoln created the Army of the Potomac to defend the federal capital, and thousands of soldiers came to the area. The significant expansion of the federal government to administer the war—and its legacies, such as veterans' pensions—led to notable growth in the city's population.

Slavery was abolished throughout the District on April 16, 1862 — eight months before Lincoln issued the Emancipation Proclamation — with the passage of the Compensated Emancipation Act.

Throughout the war, the city was defended by a ring of military forts that mostly deterred the Confederate army from attacking. One notable exception was the Battle of Fort Stevens in July 1864 in which Union soldiers repelled troops under the command of Confederate General Jubal A. Early. This battle was the only time that a U.S. president came under enemy fire during wartime when Lincoln visited the fort to observe the fighting.

On April 14, 1865, just days after the end of the war, Lincoln was shot in Ford's Theater by John Wilkes Booth during the play Our American Cousin. The next morning, at 7:22 AM, President Lincoln died in the house across the street, the first American president to be murdered. Secretary of War Edwin M. Stanton said, "Now he belongs to the ages."

Just before the war, developers began creating suburbs inside the District but outside of the city of Washington, in the unsettled land of Washington County. This sectioning of the District made it increasingly hard to administer as a single entity. In 1871, Congress created a single legislature for the entire District, with representatives from Georgetown, Washington City, and Washington County. When this too had proved unruly, Congress passed the DC Organic Act of 1878, which merged Georgetown and Washington County into Washington City — making the city's boundaries identical with those of the District of Columbia.

The District was also given a territorial government in 1871. Its second governor, Alexander Robey Shepherd, however, gained an unfortunate reputation as an extravagant boss. His ambition was to make Washington a city of opulence and luxury, which he pursued by paving streets and sidewalks, installing street lights, and introducing electrical systems. He succeeded in many of these endeavors, but led the city to bankruptcy in the process. His excesses led Congress to abolish his office in favor of direct rule; Congressional governance of the District would continue for a century.

In the early 1880s, the Washington Canal was filled in. Originally an expansion of Tiber Creek, the Canal connected the Capitol with the Potomac, running along the north side of the Mall where Constitution Avenue is today. However, as the nation transitioned over to railroads for its transport, the Canal had become nothing more than a stagnant sewer, and so it was removed. Some reminders of the Canal still exist. There are two lock buildings along the Mall, near 19th Street and Constitution. There is also a road named Canal Street that runs south from the Capitol building to the Anacostia River (although the northernmost section of the street was renamed Washington Avenue to commemorate the state of Washington).

The Washington Monument, after four decades of construction, finally opened in 1888 — the tallest building in the world at that time. Plans were laid to further develop the monumental aspects of the city, with work contributed by such noted figures as Frederick Law Olmsted and Daniel Burnham. However, development of the Lincoln Memorial and other structures on the National Mall did not get underway until the early 20th century.

One of the most important Washington architects of this period was the German immigrant Adolf Cluss. From the 1860s to the 1890s, he constructed over 80 public and private buildings throughout the city, including the National Museum, the Agriculture Department, Sumner and Franklin schools.

President Herbert Hoover ordered the United States Army on July 28, 1932, to forcibly evict the "Bonus Army" of World War I veterans that gathered in Washington, D.C., to secure promised veterans' benefits early. U.S. troops dispersed the last of the "Bonus Army" the next day.

In 1952, the city was involved in the 1952 Washington DC UFO incident. This incident resulted in the CIA directed Robertson Panel to be implemented.

A shooting at the U.S. Capitol occurred in 1954 when four Puerto Rican nationalists fired into the floor of the House of Representatives. Five representatives were wounded; one severely.

Parks and recreation facilities in Washington, D.C. remained segregated until 1954, with desegregation of public schools soon thereafter. When the city's Board of Education began building the John Phillip Sousa Junior High, a group of parents from the Anacostia neighborhood petitioned to have the school admit both black and white students, but when it was constructed the Board declared that only whites would be allowed there. The parents sued in a case that was decided in the landmark Supreme Court case Bolling v. Sharpe. Partly due to the District's unique status under the Constitution, the court decided unanimously that all of D.C.'s public schools had to be integrated. In the wake of this and the landmark 1954 Supreme Court case Brown v. Board of Education, the Eisenhower administration decided to make D.C. schools the first to integrate as an example to the rest of the nation. In 1957, Washington became the first major city in the United states with a majority African-American population.

On August 28, 1963, Washington took center stage in the American Civil Rights Movement, with the March on Washington and Martin Luther King, Jr.'s famed "I Have a Dream" speech at the Lincoln Memorial. Following the assassination of Martin Luther King, Jr. on April 4, 1968, Washington was devastated by the riots that broke out in the U Street neighborhood and spread to other neighborhoods, including Columbia Heights. The civil unrest drove not only whites, but middle-class blacks out of the city core, and caused many businesses to leave the downtown and inner city areas. Marks of riots scarred some neighborhoods into the late 1990s.

The Twenty-third Amendment to the United States Constitution, ratified on March 29, 1961, gave the people of Washington, D.C. the right to choose electors for president and vice president of the United States. The amendment states that the District shall be treated as though it were a state for all purposes relevant to the election of the president and vice president; and, specifically, that it shall have as many electors to which it would be entitled if it were a state, except that it cannot have more electors than the least populous state. However, the least number of electors any state can have is three, so the least number of representatives the District can have is three.

If the District were a state, it would currently be represented in Congress by two senators and one Member of Congress, for a total Congressional representation of 3. Thus, the District is entitled to 3 electoral votes, which is the least number of electoral votes any state can have. There have been other times in history, however — and may be again — when the District of Columbia would have been entitled to 4 electors if it were a state; but so long as it is not a state, it can have no more electors than the number allocated to the least populous state. There are currently seven states that are only entitled to 3 electors, so that situation is not likely to change in the foreseeable future.

In 1973, Congress passed the District of Columbia Home Rule Act, ceding some of its power over the city to a new, directly elected city council and mayor. Voters chose Walter Washington to become the first elected mayor of Washington, D.C. and the first black mayor of a major American city.

The first 4.6 miles (7.4 kilometers) of the Washington Metro subway system opened on March 27, 1976, following years of acrimonious battles with Congress over funding and highway construction.

On March 9, 1977, twelve African-American gunmen identified as Hanafi Muslims seized three buildings in central Washington, seeking to stop the screening of the movie Mohammad, Messenger of God and also to have certain prisoners released to them. Two people were killed, others injured, and others taken hostage for 39 hours.

In 1978, Congress sent the District of Columbia Voting Rights Amendment to the states for ratification. This amendment would have granted the District representation in the House, Senate, and Electoral College as if it were a state. The proposed amendment had a seven-year limit for ratification, and only sixteen states ratified it before the time limit expired.

Marion Barry became the city's second elected mayor after defeating Walter Washington in the 1978 Democratic Party primary. Mayor Barry was popular among low-income residents of the District for his commitment to providing summer youth employment opportunities. Initiated during his administration, the Summer Youth Employment program exists to this day.

On January 13, 1982, Air Florida Flight 90 crashed into the 14th Street Bridge shortly after takeoff from Washington National Airport in nearby Arlington, Virginia, killing 78 and destroying a portion of the bridge. The rebuilt portion was named the Arland D. Williams Jr. Memorial Bridge in honor of a heroic victim of the disaster.

During his third term, Barry was arrested for drug use in an FBI sting on January 18, 1990. He was acquitted of felony charges but was convicted on one misdemeanor count of cocaine possession, for which he served a six-month jail term. On January 2, 1991, Sharon Pratt Kelly (elected as Sharon Pratt Dixon but married later that year) was sworn in as mayor, becoming the first black woman to lead a city of that size and importance in the United States.

Marion Barry defeated Kelly in the 1994 primary and was once again elected mayor. He ended his fourth term politically weakened, however, as the city nearly became insolvent and lost much home rule authority to the Congressionally created D.C. Financial Control Board. The greatest shake-up during this period, however, did not affect Barry's power directly but concerned the D.C. Public Schools. In the autumn of 1996, the superintendent of schools and all members of the elected D.C. Board of Education were permanently relieved of responsibility. A retired U.S. Army general was brought in to serve as interim CEO of the public schools. Barry did not run for re-election again.

The next mayor, Anthony Williams, a Yale University-educated lawyer, had been appointed the city's chief financial officer by the control board. He was elected mayor in 1998 and, despite alleged mismanagement and fraud in his campaign which led to the removal of his name from the ballot, Williams won reelection in 2002 as a write-in candidate.

The Washington area was a main target of the September 11, 2001 attacks. One hijacked airplane was crashed into the Pentagon in Arlington County, Virginia, just across the Potomac River from Washington. The crash killed 64 aboard the plane and 125 people on the ground. Hijackers of United Airlines Flight 93, which crashed in Pennsylvania, supposedly intended to target either the White House or the U.S. Capitol.

Since September 11, 2001, a number of high-profile incidents and security scares have occurred in Washington. In October 2001, anthrax attacks, involving anthrax-contaminated mail sent to numerous members of Congress, infected 31 staff members, and killed two U.S. Postal Service employees who handled the contaminated mail at the Brentwood sorting facility. During three weeks of October 2002, fear spread among residents of the Washington area, with the Beltway Sniper attacks. Ten apparently random victims were killed, with three others wounded before John Allen Muhammad and Lee Boyd Malvo were arrested on October 24, 2002. In 2003 and 2004, a serial arsonist set over 40 fires, mainly in the District and inner-Maryland suburbs, with one fire killing an elderly woman. Thomas A. Sweatt, a fast-food manager, was arrested in the serial arson case in April 2005 and plead guilty in June of that year. In November 2003, the toxin ricin was found in the mailroom of the White House, and in February 2004, in the mailroom of U.S. Senate Majority Leader Bill Frist.

Since the September 11, 2001 attacks, security has been increased in Washington. Screening devices for biological agents, metal detectors, and vehicle barriers are now much more commonplace at office buildings as well as government buildings. After the 2004 Madrid train bombings, local authorities have decided to test explosives detectors on the vulnerable Washington Metro subway system. False alarms due to suspicious chemical or powder substances or suspected explosives have led to fairly frequent evacuations of buildings, Metro stations, and local post offices.

When U.S. forces in Pakistan raided a house suspected of being a terrorist hideout, they found information several years old about attacks on Washington, D.C., New York City, and Newark, New Jersey. It was directed to intelligence officials, and on August 1, 2004, the Secretary of Homeland Security put the city on Orange (High) Alert. A few days later, security checkpoints appeared in and around the Capitol Hill and Foggy Bottom neighborhoods, and fences were erected on monuments once freely accessible, such as the Capitol. Tours of the White House were limited to those arranged by members of Congress. Screening devices for biological agents, metal detectors, and vehicle barriers became much more commonplace at office buildings as well as government buildings and in transportation facilities. This ultra-tight security was referred to as "Fortress Washington;" many people objected to "Walling off Washington" based on information several years old. The vehicle inspections set up around the Capitol were removed in November 2004.

Washington is a virtually monolithic Democratic Party stronghold. Washington's current delegate to Congress, Eleanor Holmes Norton, and a majority of the city council are Democrats. In addition, every elected mayor in the modern era has been a Democrat. Since gaining three electoral votes in 1961, D.C. has never supported a Republican presidential candidate and its margins for Democrats are not only the largest of any state, but are also larger than any county. In 2004, John Kerry won the District's three electoral votes by a margin of 80 percentage points with 89.2% of the total vote.