Washington, 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 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 President 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., is located in the mid-Atlantic region of the U.S. East Coast. Due to the District of Columbia retrocession, the city has a total area of 68.34 square miles (177.0 km2 ), of which 61.05 square miles (158.1 km2 ) is land and 7.29 square miles (18.9 km2 ) (10.67%) is water. The District is bordered by Montgomery County, Maryland, to the northwest; Prince George’s County, Maryland, to the east; and Arlington and Alexandria, Virginia, to the south and west. The south bank of the Potomac River forms the District’s border with Virginia and has two major tributaries: the Anacostia River and Rock Creek. Tiber Creek, a natural watercourse that once passed through the National Mall, was fully enclosed underground during the 1870s. The creek also formed a portion of the now filled Washington City Canal, which allowed passage through the city to the Anacostia River from 1815 until the 1850s. The Chesapeake and Ohio Canal starts in Georgetown and was used during the 19th century to bypass the Little Falls of the Potomac River, located at the northwest edge of Washington at the Atlantic Seaboard fall line.