Where is Washington, D.C. located?

Washington, D.C. is located on the East Coast of the United States between the states of Virginia and Maryland, on the north bank of the Potomac River, about 38 miles southwest of Baltimore and 100 miles south of Philadelphia. The full official name is the District of Columbia, a federal district that is not part of any state but instead falls under the direct authority of Congress under Article I, Section 8 of the Constitution. The District was originally a 100 square mile diamond shaped territory ceded by Maryland (about 70 square miles north of the Potomac) and Virginia (about 30 square miles south of the Potomac). Virginia's portion, now Arlington County and most of Alexandria, was retroceded by Congress in 1846 in response to local agitation, reducing the District to its current 68 square miles, all on the Maryland side of the river.

The geographic setting on the Potomac River was chosen for several reasons. The location was a compromise between northern and southern interests negotiated by Thomas Jefferson, James Madison, and Alexander Hamilton in the Compromise of 1790, which combined the Residence Act of July 16, 1790 with the Funding Act assuming state Revolutionary War debts. President George Washington personally selected the exact site, partly because it was near his Mount Vernon estate and partly because it was thought to support river commerce inland to the Ohio Valley through the Potomac and the planned Patowmack Canal. The site sat at the head of navigation of the Potomac, where the river became unnavigable due to the Great Falls of the Potomac about 14 miles upstream.

The District's geographic boundaries today are shaped by the Potomac and Anacostia rivers and by Maryland on three sides. 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 southwest across the Potomac. Major bridges connect the District to Virginia including the Theodore Roosevelt Bridge, the Arlington Memorial Bridge, the 14th Street Bridge, and the Woodrow Wilson Bridge (technically Maryland to Virginia).

The District contains the federal capital city of Washington plus former independent suburbs that were merged with the city in 1871. The District's longitude is roughly 77 degrees west and latitude 38.9 degrees north, placing it at about the same latitude as Lisbon, Portugal and Athens, Greece. The climate is humid subtropical with hot summers and cold winters, including occasional severe winter storms and summer thunderstorms. The District is divided into four quadrants (NW, NE, SW, SE) centered on the U.S. Capitol.