Twelve-Mile Circle

[6] Its existence dates back to 1681, when King Charles II granted a deed to William Penn north of the already chartered Maryland.

Charles created an exception, consisting of 12 miles around New Castle and extending down the peninsula, since these lands were held by the Duke of York, who had won them in conquest from the Dutch colonists.

Later, on August 24, 1682, the Duke granted these lands to Penn as well, giving him: All that the Towne of Newcastle otherwise called Delaware and the fort therein or thereunto belonging scituate lying and being between Maryland and New Jersey in America.

[10] The arbitration did not ultimately resolve the dispute, and it has been brought to the Supreme Court of the United States on several occasions (all titled New Jersey v. Delaware), most notably in 1907,[11] 1934,[12] 1935,[13] and 2008.

[15] Regardless of the Supreme Court's admonition to the two states against further litigation on this subject, they were back before the court as late as November 2005, when New Jersey's desire to approve plans by BP to build a liquefied natural gas terminal along the New Jersey shore of the Delaware River fell afoul of Delaware's Coastal Zone Act.

[16] The court on January 23, 2006, appointed a special master to study the border dispute,[17] and on March 21, 2008, it upheld his report, which largely supported Delaware's authority.