Ellicott was born in
Bucks County, Pennsylvania, on April 17, 1765. In 1789, at approximately 24 years old, he accompanied his brothers
Andrew and
Joseph Ellicott in 1789 to the
British Province of
Upper Canada in a survey to determine the western boundary of the
State of New York. During 1791, 1792 and 1793, he assisted his brothers in the survey and mapping of the future
City of Washington and in the survey of the original boundaries of the District of Columbia, which were established in the
Boundary Markers of the Original District of Columbia. During November–December 1792, he led a survey that helped settle a boundary dispute within the present
Ontario County in
Western New York, which was resolved with the establishment of the
Preemption Line. From 1794–1797, he was employed as a surveyor and
draftsman for the
Holland Land Company, assisting his brother Joseph in surveys of the company's lands in western
Pennsylvania. In 1798, he was in charge of the company's surveys in
Western New York. He was an unsuccessful candidate for election in 1820 to the
Seventeenth Congress and succeeded by
Nathaniel Allen. ==Death==