Accomack County is a United States county located in the eastern edge of the Commonwealth of Virginia. Together, Accomack and Northampton counties make up the Eastern Shore of Virginia, which in turn is part of the Delmarva Peninsula, bordered by the Chesapeake Bay and the Atlantic Ocean. Accomac is the county seat. The Eastern Shore of Virginia was known as "Accomac Shire," until it was renamed Northampton County in 1642.