The Delaware Wedge was a tract of land fought over from 1633 until 1921. The land is only one square mile, but it crosses into 3 different lines drawn by charters. The original 1632 charter for Maryland placed the land in Delaware to the Calverts. Then in 1664 the land was taken and given to Maryland.
Then in 1681 the land was given to William Penn through the charter of Pennsylvania. The charter granted Penn the land west of the Delaware River and north of the 40th parallel. All land within 12 miles of New Castle was excluded from the charter, though. The area was poorly charted. New Castle is 25 miles south of the 40th parallel in all actuality.
Later, Penn acquired the New Castle land from the Duke of York. After that, the land was disputed between the three colonies for the next 80 years. It was finally settled, though, and the land was given to Delaware.