Banneker left the boundary survey

Banneker left the boundary survey in April 1791 within three months of its initiation because of concerns about his health and the difficulties in completing the survey at age 59. In addition, Andrew Ellicott's younger brothers, Benjamin and Joseph Ellicott, who usually assisted Andrew, were able to join the survey at that time. Banneker therefore returned to his home near Ellicott's Mills. The Ellicotts and other members of the surveying team then laid the remaining Virginia marker stones later in 1791. The team laid the Maryland stones and completed the boundary survey in 1792.