The 6th United States Congress was the 6th meeting of the legislative branch of the United States federal government, consisting of the Senate and the House of Representatives. It initially met at Congress Hall in Philadelphia, Pennsylvania and then was the first congress to meet in the new Capitol Building in Washington, D.C.. Its term was from March 4, 1799, to March 4, 1801, during the last two years of John Adams's presidency. It was the last Congress of the 18th century and the first to convene in the 19th. The apportionment of seats in House of Representatives was based on the 1790 United States census. Both chambers had a Federalist majority. This was the last Congress in which the Federalist Party controlled the presidency or either chamber of Congress.

Washington, D.C., formally the District of Columbia and commonly called Washington or D.C., is the capital city and federal district of the United States. The city is on the Potomac River, across from Virginia, and shares land borders with Maryland to its north and east. Washington, D.C., was named for George Washington, a Founding Father and the first president of the United States. The district is named for Columbia, the female personification of the nation.