Banneker left the boundary survey in April 1791 within three months of its initiation because the time that he was devoting to the project was conflicting with the time that he had expected to use to calculate an ephemeris for the year of 1792. Further, the arrival of spring required him to direct more attention to his farm than was needed during the winter. In addition, Andrew Ellicott's younger brothers, Benjamin and Joseph Ellicott, who usually assisted Andrew, had completed the New York survey and were able to join the survey of the federal district at around that time.