The north side of Delaware is formed by a 12 mile arc centered on the cupola of the courthouse in New Castle, Delaware. The south side of Pennsylvania lies on the 40th parallel (actually 39°43' N). and Maryland's eastern border is a line from a point in the center of the Delmarva Peninsula, midway from the Chesapeake Bay to the Atlantic Ocean at Cape Henlopen (now near Fenwick Island, Delaware). This is known as the Transpeninsular Line and is Delaware's southern line. From the Transpeninsular point north to the arc is the border between Delaware and Maryland. As it turned out this left an 800 acre wedge of no man's land claimed by Pennsylvania. (Remember that at the time the Penn's owned Delaware) Well, it took until 1921 until this dispute was finally resolved.