In 1813, Ellicott accepted a position as a professor for mathematics at the military academy at West Point, and the family left Lancaster and moved to West Point, New York. In 1817, Ellicott was again called upon to participate as astronomer in a field survey, namely a re-survey – agreed upon in the Treaty of Ghent – of the Collins–Valentine line. It was the last significant survey that he performed. Ellicott died three years later from a stroke in his home at West Point.