The 15th 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 in the Old Brick Capitol in Washington, D.C. from March 4, 1817, to March 4, 1819, during the first two years of James Monroe's presidency. The apportionment of seats in the House of Representatives was based on the Third Census of the United States in 1810. Both chambers had a Democratic-Republican majority.