Washington, D.C., formally the District of Columbia and also known as D.C. or Washington, is the capital city of the United States of America. Founded after the American Revolution, Washington was named for George Washington, the first president of the United States and a Founding Father. As the seat of the United States federal government and several international organizations, Washington is an important world political capital. Located on the Potomac River bordering Maryland and Virginia, the city is one of the most visited cities in the United States, with more than 20 million visitors annually.
The signing of the Residence Act on July 16, 1790, approved the creation of a capital district located along the Potomac River near the country's East Coast. The U.S. Constitution provided for a federal district under the exclusive jurisdiction of the U.S. 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. 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, including the city of Alexandria; in 1871, it created a single municipal government for the remaining portion of the district.
Washington had an estimated population of 705,749 as of July 2019, making it the 20th most populous city in the United States. Commuters from the surrounding Maryland and Virginia suburbs raise the city's daytime population to more than one million during the workweek.