New York City was the first U.S. capital under the Constitution.
The federal government began operating under the Constitution in 1789, and New York City served as the national capital from 1785 until 1790. George Washington was inaugurated there as the first president on April 30, 1789, at Federal Hall.
The capital then moved temporarily to Philadelphia in 1790. Washington, D.C., became the permanent capital in 1800, after federal offices relocated to the new federal district on the Potomac River.
Philadelphia is often selected by mistake because the Continental Congress met there and because the city served as the capital during much of the Revolutionary era. New York City is the specific answer for the first capital under the new constitutional government.