A commissioned officer in the Maryland militia, Major Andrew Ellicott was a highly accomplished surveyor who, along with Pennsylvania's David Rittenhouse, extended the Mason-Dixon line westward to its originally intended terminus at the southwest corner of Pennsylvania in 1784. English surveyors Charles Mason and Jeremiah Dixon had been forced to halt their work at the 244-mile point in 1767 due to the threat of hostile Native Americans. The following year, Ellicott was hired to revisit this survey …showed first 75 words of 373 total…

…showed last 75 words of 373 total…position of Commissioner of the survey of the international border between the United States and Spanish territories in Florida. In 1813, he was appointed by President James Monroe as an instructor of mathematics at the Military Academy at West Point. In 1817, he was called on to be the astronomer for the United States as part of the proceedings of the Treaty of Ghent, establishing the boundary of the United States and Canada concluding the War of 1812.