Border Patrol: When 3 States Fought Over the “Delaware Wedge”

The Commonwealth of Pennsylvania is home to its fair share of oddities. But one of the strangest stories involves its southern border and the controversy that surrounded it for more than a century.

The Wedge, a.k.a. Delaware Wedge, is a 1.068-square-mile triangular chunk of land that sits at the point where Pennsylvania, Delaware, and Maryland bump up against each other. Born of the shortcomings of a survey to settle another border dispute, the Wedge was disputed territory almost as soon as the colonies were established, and Delaware and Pennsylvania’s battle over the land wasn’t completely resolved until 1921.

Here’s a timeline of the birth of—and battle for—one of the country's weirdest little plots of land.

1. 1632
2. 1664
3. 1681
4. 1682
5. 1763
6. 1776
7. 1889
8. 1897
9. 1921

1632

The charter for the colony of Maryland gives the Calvert family the entire Delmarva Peninsula between the 40th parallel to the north and Watkin’s Point to the south. Basically, everything between Pennsylvania and Virginia. Several Dutch and Swedish settlements sit within this territory along the Delaware Bay and Delaware River. While the Calverts want them removed, the Crown refuses because of the foreign relations problems it would create for England. By 1655, the Dutch, led by Peter Stuyvesant, takes over the colony of New Sweden in present-day Delaware and incorporates it into New Netherland (present-day New York).

1664

The Dutch are driven from the area by British forces led by Sir Robert Carr and under the direction of the Duke of York. The duke, figuring he had won the land in battle, adds it to his proprietorship of New York (formerly New Netherland).

Cecil Calvert, 2nd Baron Baltimore and proprietor of Maryland, also claims ownership of the land, but since the Carr is the brother of King Charles II, he does not press the matter.

1681

William Penn receives his charter for Pennsylvania, which grants him a chunk of land west of the Delaware River with a southern border identical to Maryland’s northern border, the 40th parallel. Excluded from Penn’s grant is any land that falls within a 12-mile circle radiating from New Castle, land that belongs to the Duke of York in present-day Delaware. The grant demonstrates how poorly the area is charted and how little the men involved know of the area. The land grant indicates that Charles II and Penn think the 40th parallel intersects the Twelve-Mile Circle, but New Castle actually lies about 25 miles south of the 40th parallel. Additionally, the site that Penn has already chosen for his colony's capital city, Philadelphia, is also a little south of the parallel.

1682

The inconsistencies of the Pennsylvania grant stop being problems when Penn receives an additional grant for the New Castle lands from the Duke of York, referred to as the “the Lower Counties on the Delaware,” to be administered as a separate entity from Pennsylvania. While this land has been part of Maryland’s original grant, the Calverts have failed to confirm their hold on it by surveying it or establishing settlements. Penn’s claim on the Lower Counties begins almost 100 years’ worth of litigation between the Penns, Calverts, and their heirs.

1763

The fixing of the borders and settlement of the legal battles begins when the Penns and Calverts agree on some demarcations of their lands:

• The Twelve-Mile Circle around New Castle as the northern and (somewhat) western boundary of Delaware.

• The Transpeninsular Line, lying at approximately 38°27’ North, as Delaware’s southern border.

• The Tangent Line, connecting the middle of the Transpeninsular Line with the western side of the Twelve-Mile Circle, marking the border between Delaware and Maryland.

• An east-west line sitting about 15 miles south of Philadelphia, running along 39°43’ North (a compromise on the 40th parallel), as the border between Maryland and Pennsylvania. That meets the …

• North Line running from a tangent point north to 39°43’ North, marking the eastern border of Maryland.

• Any land west of the North Line that still falls within the Twelve-Mile Circle remains part of Delaware (a segment is known as the Arc Line).

The complexities of determining these borders required outside help. Astronomer Charles Mason and surveyor Jeremiah Dixon established the borders in the Penn-Calvert dispute and surveyed what became known as the Mason-Dixon Line—the supposed division between the American North and South that coincides with the current borders between Maryland and Pennsylvania and between Maryland and Delaware.

Because Pennsylvania and Delaware were both owned by the Penns, though, there was no rush to figure out which one owned this wedge. The Wedge became a lawless no-man’s land, providing shelter for illegal bootlegging and gambling operations.

1776

America gains its independence and Delaware is separated from Pennsylvania. The two states immediately begin fighting over the Wedge. Pennsylvania claims the land because it is beyond the Twelve-Mile Circle, but past Maryland’s side of the North Line. It’s neither part of Maryland nor Delaware, and so should be part of Pennsylvania by default. Delaware, meanwhile, claims it because it is below Pennsylvania’s southern border with Maryland—and while the border is not officially established there, Pennsylvania should not be allowed to dip below that line at any point. Because the Wedge is also east of the North Line, it's not part of Maryland and it defaults to Delaware.

The argument over the land continued for decades, with Delaware exercising jurisdiction over the area for most of that time, if only because the Wedge is a better geometric fit for it.

1889

A joint committee appointed by the two states awards the Wedge to Delaware.

1897

Pennsylvania recognizes Delaware’s claim to the Wedge and ratifies the committee’s decision.

1921

Delaware and the United States Congress ratify the decision and the Wedge officially becomes part of Delaware.

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A version of this story was published in 2011; it has been updated for 2025.