 In 1786, each of the thirteen states was to appoint a man to help survey the Seven Ranges in the easternmost portion of the Northwest Territory under the Land Ordinance of 1785.Ludlow was appointed to fill the vacant South Carolina surveyorship.Ludlow was one of two surveyors to stay in settlements near the Ohio River the winter of 1786-1787, and completed the survey of the seventh range, plats, and notes by August 1787.