My Carter Family originated on the Eastern Shore of Maryland in the 18th century. The name was originally McCarty or Carty. The branch that remained in Maryland seems to have continued to use the name "Carty" but the branch that moved across the border into Kent Co., DE became "Carter".
The earliest known ancestors were James McCarty and Barsheba Dean who were married in Dorchester Co., MD on 17 August, 1792. By 1800 the family was living in Caroline Co., MD, near the town of Ridgely, MD. It was their son, William Carty , who began the mixed blood line in Maryland when he married Elizabeth (last name unknown). Many of William and Elizabeth's children eventually moved across the border to join the mixed blood community in Kent Co., DE centered around the present day town of Cheswold.
Another family that later joined the Kent Co., DE mixed blood community , the Coker Family was also living in Caroline Co., MD at this time.
Excellent references for this line are to be found in the census records for Maryland and Delaware and the Carty Family Bible.