Flag of DC

Seal of DC

Washington, D.C. is the capital city of the United States of America. "D.C." is an abbreviation for the District of Columbia, the federal district coextensive with the city of Washington. The city is named after George Washington, military leader of the American Revolution and the first President of the United States.

The District of Columbia and the city of Washington are coextensive and are governed by a single municipal government, so for most practical purposes they are considered to be the same entity, though this was not always the case. As late as 1871, when Georgetown ceased to be a separate city, there were multiple jurisdictions within the District. Although there is a municipal government and a mayor, Congress has the supreme authority over the city and district, which results in citizens having a different status and less representation in government than residents of the states.

The centers of all three branches of the U.S. federal government are in the District. It serves as the headquarters for the World Bank, the International Monetary Fund, and the Organization of American States, and other national and international institutions. Washington is the frequent location of large political demonstrations and protests, particularly on the National Mall. Washington is the site of numerous national landmarks, monuments, and museums, and is a popular destination for tourists.

It is commonly known as D.C., The District, or simply Washington. Historically, it was called the Federal City or Washington City. It is easily confused with the state of Washington, located in the Pacific Northwest — to avoid this, the capital city is often called simply D.C., and the state referred to as "Washington State." The population of the District of Columbia, as of 2005 U.S. Census Bureau estimates, is 582,049 persons. The Baltimore-Washington Metropolitan Area surpasses 8 million persons. If Washington, D.C. were a state, it would rank last in area behind Rhode Island, 50th in population ahead of Wyoming, first in population density ahead of New Jersey, and 35th in Gross State Product.

The District of Columbia, founded on July 16, 1790, is a federal district as specified by the United States Constitution. The U.S. Congress has ultimate authority over the District of Columbia, though it has delegated considerable authority to the municipal government. The land forming the original District came from the states of Maryland and Virginia. However, the area south of the Potomac River (39 square miles or about 100 km²) was returned, or "retroceded," to Virginia in 1847 and now is incorporated into Arlington County and the City of Alexandria. After 1847, the remaining land that formed the area now known as the District of Columbia was formed exclusively from land that once belonged to Maryland.

Washington, D.C. is located at 38°53′42″N, 77°02′11″W (the coordinates of the Zero Milestone, on The Ellipse). According to the United States Census Bureau, the city has a total area of 68.3 square miles (177.0 km²). 61.4 square miles (159.0 km²) of it is land and 6.9 square miles (18.0 km²) of it (10.16%) is water.

Washington is surrounded by the states of Maryland (on its southeast, northeast, and northwest sides) and Virginia (on its western side); it interrupts those states' common border, which is the Potomac River's southern shore both upstream and downstream from the District. The Potomac River as it passes Washington is virtually entirely within the District of Columbia border because of colonial riparian rights between Maryland and Virginia.

The District has three major natural flowing streams: the Potomac River, the Anacostia River, and Rock Creek. The Anacostia River and Rock Creek are tributaries of the Potomac River. There are also three man-made reservoirs: Dalecarlia Reservoir, which crosses over the northwest border of the District from Maryland; McMillan Reservoir near Howard University; and Georgetown Reservoir upstream of Georgetown.

The highest point in the District of Columbia is 410 feet (125 m) above sea level at Tenleytown. The lowest point is sea level, which occurs along all of the Anacostia shore and all of the Potomac shore except the uppermost portion (the Little Falls - Chain Bridge area). The sea level Tidal Basin rose eleven feet during Hurricane Isabel on September 18, 2003.

The geographic center of the District of Columbia is located near 4th Street NW, L Street NW, and New York Avenue NW (not under the Capitol Dome, as is sometimes said.)

Geographical features of Washington, D.C. include Theodore Roosevelt Island, Columbia Island, the Three Sisters, and Hains Point.