After more than a decade of Philadelphia serving as the de-facto capital of the then-nascent United States, congress moved to its permanent meeting place in Washington D.C. on November 17, 1800.
On the Move
Throughout the early years of the United States, congress met in a total of 9 cities, with Philadelphia playing host to the continental congress the most frequently. There the founders signed the Declaration of Independence and ratified the United States Constitution. During the revolutionary war, however, they frequently had to move their meetings to evade British capture. Following the war, it served as the capital while Washington D.C. was under construction and did so until congress adjourned its session on May 14, 1800. Assembling months later at its now permanent location in Washington D.C.
The First Assembly
Although the capitol was still under construction, its north wing had been completed. This portion of the capitol held chambers for the Senate, the House of Representatives, the Library of Congress, and the Supreme Court. After congress assembled and achieved a quorum for the first time in the new building on November 17, 1800, they fulfilled the deadline previously set out by the Residence Act of 1790, which had set out provisions for the construction of a national capital and a permanent seat of governance in the new nation.
Construction continued on the capitol building for over a decade, both wings being finished shortly before the British set fire to the building and others in Washington D.C. during the War of 1812. Reconstruction began in 1815 and included redesigned chambers to accommodate a growing government.