High Quality Content by WIKIPEDIA articles! The Sixth United States Congress was a meeting of the legislative branch of the United States federal government, consisting of the United States Senate and the United States House of Representatives. It met at Congress Hall in Philadelphia, Pennsylvania and in Washington, D.C. from March 4, 1799 to March 3, 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.