Washington, D.C., officially the District of Columbia and commonly known as simply Washington or D.C., is the capital city and federal district[a] of the United States. The city is split from Virginia to its southwest by the Potomac River and shares land borders with Maryland to its north and east. It was named after George Washington, who served as the first president of the United States. The district is named for Columbia, the female personification of the nation.br br The U.S. Constitution in 1789 called for the creation of a federal district under exclusive jurisdiction of the U.S. Congress. As such, Washington, D.C., is not part of any state, and is not one itself. The Residence Act, adopted on July 16, 1790, approved the creation of the capital district along the Potomac River, and is considered the city's founding date. In 1800, when the capital was moved from Philadelphia, the 6th Congress started meeting in the then-unfinished Capitol Building, and the second president, John Adams, moved into the newly finished White House. br Washington Dulles International Airport (ˈdʌlɪs DUL-iss) (IATA: IAD, ICAO: KIAD, FAA LID: IAD) – commonly known simply as Dulles Airport – is an international airport in the Eastern United States primarily serving the country's capital city, Washington, D.C. and its surrounding area. It is located 26 miles (42 km) west of downtown Washington, D.C., in Loudoun and Fairfax counties in Northern Virginia.[4][5]br br Opened in 1962, the airport is named after John Foster Dulles, an influential secretary of state during the Cold War who briefly represented New York in the United States Senate.[6][7] Operated by the Metropolitan Washington Airports Authority, Dulles occupies 13,000 acres (20.3 sq mi; 52.6 km2),[2][8] straddling the Loudoun–Fairfax line.[9] IAD ranks fourth in the US in terms of land area, after Denver International Airport, Dallas Fort Worth International Airport, and Southwest Florida International Airport. Most of the airport is in the unincorporated community of Dulles in Loudoun County, with a small portion in the unincorporated community of Chantilly in Fairfax County. The Town of Herndon is the closest municipality to the airport.br br Along with Ronald Reagan Washington National Airport (DCA) and BaltimoreWashington International Airport (BWI), Dulles is one of three major airports serving the Washington–Baltimore metropolitan area. As of 2024, it is the busiest airport in the Washington–Baltimore metropolitan and the 24th-busiest airport in the United States.[10] Dulles has the most international passenger traffic of any airport in the Mid-Atlantic outside the New York metropolitan area, including approximately 90 of the international passenger traffic in the Baltimore–Washington region.[11] It had more than 20 million passenger enplanements every year from 2004 to 2019, with 27.3 million enplanements in 2024.[12] An average of 60,000 passengers pass through Dulles.