Answer:
The first city that was the seat of government for the colonies was Philadephia, Pennsylvania, including the government under the Articles of Confederation.
Following the Revolutionary War, the first Congress under the Articles of Confederation met at the City Hall, Federal Hall in New York, in 1785, and also the 1st US Congress following the ratification of the US Constitution in 1789. The government again met in Philadelphia's Congress Hall from 1790 to 1800.
In 1800, President John Adams directed the relocation of the government to the newly built city of Washington in the District of Columbia.