Accomac was the first name for the Eastern Shore settlements of the English, and of the county originally created in 1634. In 1643 the General Assembly changed the county name to Northampton, perhaps as part of the purge of native American names like Warrosquyoake.
In March, 1661/62, there were enough English settlers travelling long distances to the monthly courts to justify dividing Northampton into two counties. The southern half retained the name of Northampton, and the northern half adopted the old name of Accomac.