{"id":497,"date":"2008-11-09T13:44:14","date_gmt":"2008-11-09T18:44:14","guid":{"rendered":"http:\/\/www.howderfamily.com\/blog\/?p=497"},"modified":"2022-01-11T07:36:11","modified_gmt":"2022-01-11T12:36:11","slug":"the-twelve-mile-circle-part-ii","status":"publish","type":"post","link":"https:\/\/www.howderfamily.com\/blog\/the-twelve-mile-circle-part-ii\/","title":{"rendered":"The Twelve Mile Circle, Part II"},"content":{"rendered":"\n

An arc-shaped portion of the border between Delaware and Pennsylvania<\/a> serves as the most visible manifestation of the so-called Twelve Mile Circle, as noted in the previous entry. However other impacts can also be discerned. The oddity also effects the Delaware – New Jersey boundary, albeit less visibly.<\/p>\n\n\n\n

Refer back to the map again and let’s reacquaint ourselves with the layout:<\/p>\n\n\n\n

\"Twelve<\/a><\/figure>\n\n\n\n
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A Complicated River Border<\/h2>\n\n\n\n

Imagine in your mind’s eye a complete circle and notice where it crosses the Delaware River on the north and on the south. Delaware’s territory extends right up to the mean low tide mark on the eastern riverbank within the circle. In contrast, Delaware and New Jersey split ownership of the river using the thalweg method outside of the circle.<\/p>\n\n\n\n

I have a previous entry that describes various methods of splitting river borders<\/a> so go there if you’d like a more detailed explanation. As unusual as it sounds, the two states have a different basis for dividing their river boundary depending on whether one is inside or outside of the 12-mile circle.<\/p>\n\n\n\n

Other than being a geographic curiosity and a great trivia question, does it really matter? Indeed it does, and it comes with a lot of implications. First, Delaware owns all of river islands within the circle.<\/p>\n\n\n\n

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Pea Patch Island<\/h2>\n\n\n\n
\"Fort
Fort Delaware on Pea Patch Island<\/figcaption><\/figure>\n\n\n\n

Pea Patch Island is one of those islands and today it’s the site of Fort Delaware State Park (map<\/a>). I have an interest in coastal defenses and fortification and I was fortunate enough to visit here<\/a> a few years ago. Pea Patch Island emerged as a mud bank in the 18th<\/sup> Century. By the early 19th<\/sup> it had grown large enough for the U.S. Military to construct a fort on the site. It was designed to help defend the river and the approach to important commercial centers such as Wilmington and Philadelphia.<\/p>\n\n\n\n

It never saw action but it did serve as a prison for captured Confederate soldiers during the Civil War. Pea Patch Island increased further in size when the Army Corps of Engineers dredged a shipping channel nearby and used it as a convenient dumping spot for fill dirt. More germane to our topic though — and since Pea Patch Island falls within the circle — all 288 acres automatically belong to Delaware.<\/p>\n\n\n\n

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Practical Exclaves<\/h2>\n\n\n\n

There are even portions of Delaware on the “wrong” side of the river, accessible by land only from New Jersey. One such instance happens here:<\/p>\n\n\n\n