York County Gets A Toehold

The colony of South Carolina was founded in 1670, and was divided into three counties 12 years later. Craven County, which roughly encompassed the northern half of South Carolina, included the southern half of present-day York County, while the top portion of present-day York County was considered part of North Carolina.
Before the boundary between the two Carolinas was fixed in 1772, the northern portion of York County was originally part of Bladen County, North Carolina. In 1750 it was included in the newly created Anson County, North Carolina; the first land grants and deeds for the region were issued in Anson County.
In 1762 Mecklenburg County, North Carolina was formed from western Anson County, and included present-day northern York County. Five years later the area became part of Tryon County, which comprised all of North Carolina west of the Catawba River and south of Rowan County. The area would remain a part of Tryon County until 1772, when the boundary between North and South Carolina was finally established.
After its transfer to South Carolina in 1772, much of the area was known as the New Acquisition. In 1785, York County was one of the original counties in the newly created South Carolina, and its boundaries remained unchanged until 1897, when a small portion of the northwestern corner was ceded to the newly-formed Cherokee County.

(Source: Wikipedia)