Read more : WikipediaWashington, D.C., formally the District of Columbia and commonly referred to as “Washington”, “the District”, or simply “D.C.”, is the capital of the United States. The signing of the Residence Act on July 16, 1790, approved the creation of a capital district located along the Potomac River on the country's East Coast. The U.S. Constitution provided for a federal district under the exclusive jurisdiction of the Congress and the District is therefore not a part of any U.S. state.
The states of Maryland and Virginia each donated land to form the federal district, which included the pre-existing settlements of Georgetown and Alexandria. Named in honor of George Washington, the City of Washington was founded in 1791 to serve as the new national capital. In 1846, Congress returned the land originally ceded by Virginia; in 1871, it created a single municipal government for the remaining portion of the District.
Washington, D.C., had an estimated population of 658,893 in 2014, the 23rd-most populous city in the United States. Commuters from the surrounding Maryland and Virginia suburbs raise the city's population to more than one million during the workweek. The Washington metropolitan area, of which the District is a part, has a population of 5.8 million, the seventh-largest metropolitan statistical area in the country.
The centers of all three branches of the federal government of the United States are in the District, including the Congress, President, and Supreme Court. Washington is home to many national monuments and museums, which are primarily situated on or around the National Mall. The city hosts 176 foreign embassies as well as the headquarters of many international organizations, trade unions, non-profit organizations, lobbying groups, and professional associations.