Washington, D.C., became the permanent capital of the United States when Congress first met there in 1800.
The Residence Act of 1790 selected a site on the Potomac River for the national capital. President George Washington chose the general location, and Pierre Charles L’Enfant prepared an ambitious plan for the federal district. The city was named Washington in honor of the first president.
The federal government moved from Philadelphia to the new capital in 1800. President John Adams moved into the unfinished White House on November 1, and Congress convened there on November 17. The District of Columbia was organized as a federal district rather than a state.
New York City had been the first national capital under the Constitution, and Philadelphia served as the temporary capital from 1790 to 1800. Those earlier capitals are why Washington, D.C., was not the country’s first capital.