Ellicott's Stone marks the first southern boundary of the United States and the Mississippi Territory created in 1798, nine hundred feet east of a stone marked 31° North Latitude that separated the U.S. and Spanish Florida. This line of demarcation ran from the Mississippi east along the 31st parallel to the Chattahoochie River, then down that river to the mouth of the Flint River, then on a line to the headwaters of the St. Mary’s River, then down that river to the Atlantic Ocean. Major Andrew Ellicott, appointed by George Washington as U.S. Commissioner to survey the boundary as defined in the Treaty of San Lorenzo (1795), was engaged in this expedition from 1796-1800. Esteban Minor was appointed commissioner on the Spanish side. In 1803, the Ellicott Stone was selected as the Initial Point to begin the U.S. Public Land Surveys that control land boundaries in southern Alabama and Mississippi (St. Stephens Meridian).