The 6th United States Congress was a meeting of the legislative branch of the United States federal government, consisting of the Senate and the House of Representatives. It met at Congress Hall in Philadelphia, Pennsylvania and in Washington, D.C. 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 First Census of the United States in 1790. Both chambers had a Federalist majority. This was the last Congress in which the Federalist Party controlled the presidency or either chamber of Congress.