The Wedge (or Delaware Wedge) is a 1.068-square-mile (2.77 km2) tract of land along the borders of Delaware, Maryland and Pennsylvania. Ownership of the land was disputed until 1921; it is now recognized as part of Delaware. The tract was created primarily by the shortcomings of contemporary surveying techniques. It is bounded on the north by an eastern extension of the east-west portion of the Mason–Dixon line, on the west by the north-south portion of the Mason–Dixon line, and on the southeast by the New Castle, Delaware, Twelve-Mile Circle. The crossroads community of Mechanicsville, Delaware, lies within the area today.
The original 1632 charter for Maryland gave the Calverts what is now called the Delmarva Peninsula above the latitude of Watkins Point, Maryland up to the 40th parallel. A small Dutch settlement, Zwaanendael (1631–32), was within their territory, as were the later New Sweden and New Netherland settlements along the Delaware Bay and Delaware River. Although the Calverts publicly stated that they wanted the settlements removed, they did not confront them militarily because of the foreign policy implications for the Crown.
In 1664, the Duke of York, brother of King Charles II, removed foreign authority over these settlements, but in the process the Crown eventually decided that the area around New Castle and the land below it on the Delaware Bay should be separated from Maryland and administered as a new colony.
In 1681, William Penn received his charter for Pennsylvania. This charter granted him land west of the Delaware River and north of the 40th parallel, but land within 12 miles (19 km) of New Castle was excluded. This demonstrates how poorly charted this area was, as New Castle is actually about 25 miles (40 km) south of the 40th parallel. The Penns later acquired the New Castle lands from the Duke of York, which they called the Three Lower Counties and are now known as Delaware. Delaware, however, remained a distinct possession from Pennsylvania.