Surveying team in western New York

In February 1791, surveyor Major Andrew Ellicott (the son of Joseph Ellicott and cousin of George Ellicott), having left at the request of U.S. Secretary of State Thomas Jefferson a surveying team in western New York that he had been leading, hired Banneker as a replacement to assist in the initial survey of the boundaries of a new federal district. Formed from land along the Potomac River that the states of Maryland and Virginia ceded to the federal government of the United States in accordance with the 1790 federal Residence Act and later legislation, the territory that became the original District of Columbia was a square measuring 10 miles (16 km) on each side, totaling 100 square miles (260 km2). Ellicott's team placed boundary marker stones at or near every mile point along the borders of the new capital territory.