The First United States Congress began meeting under the new Constitution on March 4, 1789.
The First Congress met at Federal Hall in New York City during the first two years of George Washington’s presidency. Its formal term began on March 4, although the House of Representatives did not achieve a quorum until April 1 and the Senate reached a quorum on April 6.
The Congress organized the new federal government, created executive departments, established the federal judiciary through the Judiciary Act of 1789, and approved the Bill of Rights for submission to the states. Washington was inaugurated on April 30, 1789, after Congress had begun its constitutional work.
March 4 is sometimes mistaken for the inauguration date or for the date the Constitution was signed. It was the scheduled starting date for the new government under the constitutional system. The First Congress later met in Philadelphia after the national capital moved there.