The Treaties of Portage des Sioux were a series of treaties at Portage des Sioux, Missouri in 1815 that officially were supposed to mark the end of conflicts between the United States and Native Americans at the conclusion of the War of 1812. The earlier treaties included the Treaty of St. Louis (1804) in which the Sac and Fox ceded a swath of land from Missouri through Illinois and Wisconsin and the Treaty of Fort Clark in 1808 in which the Osage Nation ceded Missouri and Arkansas west of Fort Clark. The treaty signings at Portage des Sioux were to occur between July 18 and September 16.