Washington, D.C., became the capital of the United States in 1800.
The Residence Act of 1790 authorized a permanent capital on the Potomac River. President George Washington selected the site, which lay near the boundary between Maryland and Virginia. French engineer Pierre Charles L’Enfant prepared an influential plan for the new federal city.
The federal government moved from Philadelphia to Washington in June 1800. The Capitol and the White House were not yet fully complete, but the government began operating in the new district. John Adams was the first president to occupy the White House, while Thomas Jefferson became the first president inaugurated there in 1801.
Washington, D.C., is a federal district rather than a state. The abbreviation “D.C.” means District of Columbia, a name associated with Christopher Columbus and widely used for the planned capital district.