New York City was the first capital of the United States under the Constitution.
The new federal government began operating there in 1789. George Washington was inaugurated at Federal Hall on April 30, 1789, and the first Congress met in the same city. Federal Hall stood on Wall Street in lower Manhattan.
New York City had also served as the national capital under the Articles of Confederation during the 1780s. The capital moved to Philadelphia in 1790 under a compromise connected with federal assumption of state debts. Congress later selected the Potomac site for a permanent capital, and the government moved to Washington, D.C., in 1800.
Philadelphia is therefore an important founding-era capital, but it was the second capital under the Constitution, not the first. Washington, D.C., became the permanent capital rather than the initial seat of the new constitutional government.