
Multiple colonial charters, two negotiated settlements by the states in 1785 and 1958, an arbitrated agreement in 1877, and several Supreme Court decisions have defined how Maryland and Virginia would deal with the Potomac River as a boundary line, and shaped the boundary on the Eastern Shore (separating Accomack County in Virginia from Worcester/Somerset counties in Maryland).
The Potomac River divides Maryland and Virginia, but Virginia does not own half of the Potomac River. The Maryland-Virginia boundary is next to the Virginia shoreline at the low-water mark in most places; the line separating Maryland from Virginia is not in the middle of the river.
As a result of this peculiar boundary:
- in the 1950's, when gambling and liquor-by-the-drink were legal in Maryland but not Virginia, Colonial Beach and Prince William County had slot machines located on boats docked in the river off the Virginia shoreline. (Customers would park in Virginia, walk out a pier, and "step across the line" into Maryland.)
- today, if you want to get married on a boat in the middle of the Potomac River while looking at Mount Vernon, you need a Maryland marriage license.
- bridges crossing the Potomac River are almost completely in Maryland... and the dreams of Virginia transportation planners to build new bridges across the Potomac River in Loudoun/Prince William counties can be blocked by Maryland, which has expressed clear opposition to road projects that would extend urban sprawl further into Montgomery/Charles counties.

Between 1606-1609, in the three charters issued by James I, most of what is now Maryland was included within the boundaries of the Virginia colony. After James I revoked Virginia's charter in 1624 and converted it into a royal colony, there were no constraints on how the king could alter the boundaries of Virginia.
In 1632, King Charles I reduced the size of Virginia when he granted a charter to Cecil Calvert, Baron of Baltimore. Virginia lost control of the northern part of the Delmarva Peninsula and the top of the Chesapeake Bay, plus all land north of the Potomac River. The Calverts named their new colony after the wife of Charles I, Queen Henrietta Maria. An earlier colony founded by George Calvert on the island of Newfoundland was called Avalon, but Maryland provided some political advantage by honoring the king's wife. Virginia colonists had sought royal favor in the same way, naming their colony after the "virgin queen" Elizabeth and naming the first town after James I.
The original plan of Charles I had been to reward Cecil Calvert's father George. George Calvert had considered asking the king for land between the James and Chowan rivers, picking off the southern end of the Virginia colony. Virginia officials, and others in England who hoped to obtain their own grant for the Carolinas, steered Calvert and King Charles' officials into choosing land far to the north of the Virginia settlements on the James River. Encouraging Calvert's Catholic settlers to occupy the uncolonized land north of the Potomac River would help England compete with the Dutch, who were starting to settle in the gap between New England and Virginia. (The area was not "unoccupied," but land claims by Native Americans were not a factor in drawing the boundaries of English colonial charters.)1
George Calvert anticipated getting the entire Delmarva Peninsula in his grant. However, he died before the paperwork was finalized, and royal officials realized that Virginia colonists had already settled in what today are Accomack and Northampton counties. When George's son Cecil Calvert got his charter for Maryland, the Maryland boundary on the Eastern Shore was drawn from Watkins Point east to the Atlantic Ocean. The southern part of the Eastern Shore was excluded and remained within the Virginia colony's boundaries.2
![]() the 1632 Maryland charter defined the new colony's southern boundary on the Eastern Shore starting at a point in the Chesapeake Bay, then by a Right Line drawn from the Promontory, or Head-Land, called Watkin's Point, situate upon the Bay aforesaid, near the river Wigloo, on the West, unto the main Ocean on the East (NOTE: map is oriented with West at the top, and North is to the right) Map Source: Library of Congress, Virginia / discovered and discribed by Captayn John Smith, 1606 |
![]() Delmarva Peninsula, without political boundaries later imposed by English officials Map Source: US Fish and Wildlife Service, Wetlands Mapper |

The northern boundary of the new colony of Maryland was defined by drawing a line due west from the ocean along the 40 degree parallel, the southern boundary of the New England grants, until getting to a point due north of the beginning of the Potomac River. In reality, the line was located further north, where Philadelphia is now located. After William Penn was granted a charter for a new colony in 1681, Maryland and Pennsylvania argued about their border until a survey was completed in 1767 by Charles Mason and Jeremiah Dixon, the Mason-Dixon Line.

The western boundary of Maryland was based on the location where the Potomac River started, along a line running directly south from the 40th parallel (at least that's what they thought in 1632...) to the spring at the headwaters of the Potomac River. The Deakins Line was surveyed in 1788, starting at the sandstone monument (the "Fairfax Stone") that had been erected in 1746 and moving north to the Pennsylvania-Maryland line.
As defined in the 1632 charter, the Maryland boundary crossed the river to the southern bank. Key language in the grant from Charles I was that Maryland's western boundary kept going south and crossed the Potomac River to its southern shore, before following the southern edge of the Potomac River to the Chesapeake Bay. The western boundary extended:3
![]() Maryland's border was defined in 1632 charter by a line running south from 40th parallel (supposedly...) to the start of the Potomac River, then unto the further Bank of the said River before following the southern edge of the Potomac River to the Chesapeake Bay Map Source: US Fish and Wildlife Service, Wetlands Mapper |
No one knows why the 1632 charter was so generous to Maryland, giving the entire Potomac River to Maryland instead of drawing the boundary in the middle of the river. The decision may have been intended to give Maryland officials an extra measure of control. George Calvert had visited Jamestown with his family in 1629, and the Virginia colonists had demonstrated their distrust of him both as a Catholic and a potential rival.
Another possibility is that no one in London cared much about the details of the boundaries, far across the Atlantic Ocean. At least some people thought the boundary should be drawn at Potomac Creek or Aquia Creek, in modern Stafford County. It is hard to believe such efforts reflected ignorance of which stream was the main Potomac River. The first European known to have explored the area, John Smith, had clearly recognized in 1608 which creeks were smaller tributaries and which channel was the main stem.
![]() if Potomac Creek/Aquia Creek had been declared the main stem of the Potomac River, all of Northern Virginia would have been part of Maryland Source: Library of Congress, A mapp of Virginia discovered to ye hills, and in it's latt. from 35 deg. & 1/2 neer Florida to 41 deg. bounds of New England (by John Ferrar, around 1667) |
![]() first map showing Maryland drew boundary on south side of Aquia Creek in modern Stafford County, so current Northern Virginia could have been Southern Maryland Source: Maryland State Archives, Nova Terrae-Mariae tabula (by Jerome Hawley and John Lewger, 1635) |
Complicating the status of the river, in 1688 James II modified the boundaries of the "Northern Neck" grant made originally by Charles II in 1649, and renewed as the Hopton grant in 1667. James II gave Lord Culpeper the entire Potomac River in 1688:4
In 1776, the first Constitution of Virginia acknowledged that the Maryland charter was valid, but avoided defining the limits of that state's claim to the Potomac River. The 1776 Virginia constitution did assert the right of Virginians to exercise free navigation on the Potomac and Pokomoke rivers, and to use the water and shoreline ("riparian rights"):5
Left unclear was determination of the location of the actual line on the south bank, the "further Bank of the said River" (in Latin, ad ulterioram predicti fluminis ripam).
Virginians were not legalistic about defining the edge of the shoreline, or even respectful of Maryland's claim to the entire river. In tidewater, the rise and fall of the tides can produce a wide, sandy beach/mudflat on the river's edge. Above the high water mark, defined by the edge of vegetation along the shoreline, the upland was clearly Virginia. Below the low water mark (the normal edge of the water when the tide is out, "the point to which the water recedes at its lowest stage" according to Black's Law Dictionary), the riverbottom was clearly Maryland. The shoreline itself could be interpreted as being in Virginia - or in Maryland.6
A literal interpretation of the 1632 grant to Lord Baltimore might suggest the boundary was set at the high water mark, but Virginia landowners interpreted the right to "navigation and use" of the Potomac to include using the shoreline down to the low water mark. Wharfs were built on the shore at plantations such as Stratford Hall, with no consideration of paying Maryland taxes for the shoreline real estate. George Washington operated a herring fishery in the Potomac River offshore from Mount Vernon. It provided a more reliable source of income than growing tobacco and wheat, but he never asked for permission or paid Maryland anything for "their" fish.7


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After the American Revolution, the new United States was only a loose confederation, governed by a weak national Congress. Maryland had refused to ratify the Articles of Confederation until 1781, maneuvering Virginia and other states into ceding their western lands claims (beyond the Ohio River) to the new national government first. Maryland could have asserted its right as an independent state and its claim to the Potomac River, and tried to tax commercial traffic going to Virginia ports such as Alexandria.
However, it was not clear how Maryland could enforce any claim based on the now-rejected authority of English kings. Virginia still remained the largest, most-populated state in the new nation, and the "United States in Congress Assembled" under the Articles of Confederation might not suport ancient land grant claims by Maryland against Virginia. In 1785, there was no judicial referee to resolve interstate conflicts. The idea of a Supreme Court, operating as an independent third branch of government, would not be established until the Constitution was ratified in 1788 and the court asserted its independence over the next 20 years. It was unclear how a weak national Congress could force Virginia to comply with Maryland's interpretation of its 1632 charter. Besides, Virginia had real leverage to convince Maryland to resolve conflicting claims to use of the Potomac River: Virginia owned the mouth of the Chesapeake Bay. Virginia was an independent state that could tax all Maryland ships coming from the Atlantic Ocean into the Chesapeake Bay, before they sailed north to "Maryland's" Potomac River. The tradeoffs to reach agreement were based on the shape of the bay as well as the colonial boundaries. While Maryland might own the Potomac River, Virginia controlled the entrance to the Chesapeake Bay. Under the Articles of Confederation, Virginia could impose a high tax on all vessels sailing between Cape Charles and Cape Henry on the way to the Potomac River. All of Maryland's significant ports were on the bay and the rivers draining into the bay, such as Annapolis and Baltimore. There were no good harbors on Maryland's Atlantic coastline. As a result of natural and political geography, nearly all commercial traffic going to (or from) Maryland could be forced to pay an import or export fee on their cargoes passing through Virginia's portion of the Chesapeake Bay. Bottom line: each state could wreak economic havoc on the other. |

The solution was to negotiate, in order to encourage rather than block each state's commerce and economic development. Maryland supported chartering the Potowmack Company in 1784, which would benefit both states, and agreed to send delegates in 1785 to a meeting regarding commercial use of the river.
Each state appointed commissioners to negotiate a compact. The commissioners met initially in Alexandria, then moved to Mount Vernon. In part because George Washington hosted the discussions (even though the Virginia General Assembly had not designated him as a commissioner), the negotiators crafted the Compact of 1785 and the General Assemblies of both states ratified the deal.
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Maryland and Virginia agreed in the Compact of 1785 that neither state could interfere with the other's trade or fishing on the Potomac River. Virginia and Maryland also agreed to allow each other free access on the Chesapeake Bay. The first provision in the Compact of 1785 stated:8
Through that statement, Virginia traded away its theoretical ability to impose tolls on Maryland vessels entering the Chesapeake Bay between Cape Charles and Cape Henry, near Norfolk. In exchange, Virginia was guaranteed free access to the Potomac River. The challenges in resolving the Virginia/Maryland issues through bi-state negotiations revealed clearly that the new national government was not capable of dealing with multi-state concerns. To comply with the Articles of Confederation, Virginia and Maryland were supposed to get approval by a majority of the Congress, where other states could be competitive rather than cooperative and potentially block commercial development in the Chesapeake Bay region:9 The commissioners called for another meeting among all the states to address larger interstate commerce issues. This led to the Annapolis Convention, which begat the Constitutional Convention in Philadelphia in 1787, which begat the Constitution and the current political structure for the United States of America. The Virginia/Maryland border dispute triggered the conflict resolution process that led to the Commerce Clause authorizing the new Federal Government to "regulate commerce with foreign nations, and among the several states, and with the Indian tribes." |
![]() when the Compact of 1785 was negotiated, the economies of Virginia and Maryland were both dependent on exporting tobacco by ships to Europe Source: National Park Service, Jamestown, Virginia National Historic Site - The Townsite and Its Story |
To get a sense of the challenge under the Articles of Confederation to resolve the interstate conflict over the rights to the Potomac River, look at today's debates over the relative authority of individual states in the European Union. In 1785 it was not clear that the 13 new states would remain under one federal government, just as the future of the European Union is unclear today. The development of the Constitution was not pre-ordained, and the leaders of the newly-independent states had no crystal ball showing that a new Constitution would change the authorities of the individual states.
Like the Articles of Confederation, the new Constitution required that interstate compacts had to be approved by the national Congress. No two states would be allowed to cut side deals without concurrence by all the other states. However, the Compact of 1785 was "grandfathered in" because it preceded adoption of the national Constitution. (In 1958, another compact between Maryland-Virginia to resolve boundary issues was ratified by the Congress.)
| Maintaining ownership of the Potomac River was the only boundary fight in which Maryland managed to maintain most of its original claims. It lost battles with Pennsylvania to define the eastern and northern sides of the colony.
The 1632 charter for Maryland defined its boundary along the 40th parallel of latitude. The 1681 charter for Pennsylvania used the same line. The surveying surprise was that the 40th parallel was further north than expected, and ran through what became Philadelphia. If the Calverts had succeeded in blocking claims of the Penns, then Maryland might have ended up controlling all the territory south of the 40th parallel. If Maryland's claim to that line was upheld, it would control land on both sides of the mouth of the Delaware River, comparable to Virginia's control of Cape Charles/Cape Henry at the mouth of the Chesapeake Bay. All ships sailed to Philadephia through the Delaware Bay. In theory, under the Articles of Confederation, Maryland could have taxed all ships going to and from the Delaware River to the Atlantic Ocean. In reality, the Penns forced the Calverts to accept a boundary line south of Philadelphia, 15 miles below the 40th parallel. (The Mason-Dixon line ultimately defined the northern border of Maryland.) Pennsylvania also blocked Maryland from acquiring control of three counties along the western shore of Delaware Bay, territory that had been settled earlier by Swedes and Dutch. The three counties ended up becoming the separate colony of Delaware, while the eastern shore of Delaware Bay - including Cape May - ended up as part of New Jersey. |
![]() Delaware Bay and the southern 1/3 of New Jersey could have been part of Maryland Map Source: US Fish and Wildlife Service, Wetlands Mapper |
The Compact of 1785 resolved the dispute over navigation and taxation, and made clear that Smith’s Point was the mouth of the Potomac River and the starting point for the line across the Chesapeake Bay. Maryland made no effort to extend its claim south to the location of Cinquack, as marked on John Smith's map.10
However, the Compact of 1785 did not fix the location of the boundary line along the Potomac River, or clarify if the high-water mark or the low-water mark should be used. A lawsuit in the District of Columbia led to a US Supreme Court decision that determined ownership of the shoreline, and surveys that marked a fixed boundary on the southern bank of the Potomac River.
After the District of Columbia was created, the Federal government sold In the Arbitration of 1877 (the Black and Jenkins Award), arbitrators used a survey of the river to refine each state's claims. As part of the arbitration, affirmed by the US Congress in 1879, the two states formally determined that Maryland's boundary would be the low water mark. To minimize confusion about the location of the low water mark, the line was defined as a fixed boundary by the Matthews-Nelson Survey of 1927. In that survey, the state boundary did not follow the shoreline exactly. Shallow-water embayments were granted to Virginia, and the Maryland-Virginia state line crosses between points of land jutting into the Potomac River.
The 1877 arbitration decision also said "Virginia is entitled not only to full dominion over the soil to low-water mark on the south shore of the Potomac, but has a right to such use of the river beyond the line of low-water mark as may be necessary to the full enjoyment of her riparian ownership, without impeding the navigation or otherwise interfering with the proper use of it by Maryland, agreeably to the compact of seventeen hundred and eighty-five."3 The 1877 decision would have an impact on Fairfax County in 2003.

In 1829, a canal was opened to connect the northern tip of the Chesapeake Bay to the Delaware Bay. The Chesapeake and Delaware Canal bypassed the passage of Baltimore-bound shipping through Virginia, via the natural opening at Cape Charles/Cape Henry, and now carries 40% of all the shipping to the port of Baltimore.6 Had the Chesapeake and Delaware Canal been built before the Compact of 1785, ships would have been able to sail between Baltimore and the Atlantic Ocean without having to use the mouth of the Chesapeake Bay and sail through Virginia waters. Without the leverage of control over traffic in the lower Chesapeake Bay, who knows how the Maryland/Virginia negotiations over the boundary may have evolved...
In 1940, Congress gave its consent to a new interstate compact for managing the Potomac River. Maryland, West Virginia, Pennsylvania, Virginia, and the District of Columbia entered into a Congressionally-approved compact that created the Interstate Commission on the Potomac River Basin (ICPRB) and the Potomac Valley Conservancy District, to address water quality and related land resources issues in the Potomac River watershed.
In the 1950's, the dispute between Maryland and Virginia over rights to oysters and other resources in the Chesapeake Bay/Potomac River turned violent. Both states armed patrol vessels and the "Oyster Wars" led to a effort to abrogate the Compact of 1785. Virginia started a lawsuit at the Supreme Court (VIRGINIA v. MARYLAND, 355 U.S. 269), but state officials were able to negotiate their differences and replaced the Compact of 1785 with the Compact of 1958.
The 1958 agreement established the Potomac River Fisheries Commission, defined the jurisdictional boundaries for that commission's powers (in great detail for the Maryland side of the Potomac River, but simply referencing the mean low waterline of the Potomac River on the Virginia side, as marked by the Matthews-Nelson Survey of 1927). After both the Virginia and Maryland legislatures and the Maryland voters approved the 1958 agreement, Congress affirmed it in 1962.
The South Branch of the Potomac River discharges more water than the North Branch, but in 1746 the surveyors of the Fairfax Grant chose the headspring of the North Branch (with its wider valley) as the source of the Potomac River. In 1788, Francis Deakins surveyed land in western Maryland for compensating soldiers who fought in the Revolutionary War. He based his survey on the Fairfax Stone, using it to define the western boundary of the state.
However, in 1850 Maryland claimed that the western edge of the colonial grant to Virginia was the South Branch of the Potomac River, not the North Branch. In 1897, Maryland even set a Potomac Stone at the headwaters of the South Branch as a rival for the Fairfax Stone at the headwaters of the North Branch. By that time, the dispute was between West Virginia (created in 1863) and Maryland.
In 1910, the US Supreme Court ruled that the West Virginia-Maryland boundary would begin about 1 mile north of the Fairfax Stone, where the Deakins Line crossed the North Branch. As a result, the Fairfax Stone itself is completely within West Virginia, and is no longer on the border with Maryland.
The Supreme Court also determined that the low-water mark of the south bank of the Potomac River was the Maryland-West Virginia boundary, applying the logic of the 1877 arbitration agreement (the Black-Jenkins Award) between Virginia-Maryland to West Virginia. Splitting Virginia into two separate states in 1863 did not change the court's opinion of the boundary upstream from the mouth of the Shenandoah River to the Fairfax Stone. 7
West of the starting point of the North Branch of the Potomac River, the northern boundary of Virginia was the southern border of Pennsylvania, established by the Mason-Dixon Line. Mason and Dixon did not survey all the way from Delaware to the southwestern corner of Pennsylvania (near Pittsburgh), but the modern West Virginia/Pennsylvania boundary is a western extension of the actual line they surveyed in the 1760's.

While all of Maryland was once part of Virginia, the Virginians fought (physically, with guns, resulting in deaths...) to assert control over only two parts: Kent Island and the Chespeake Bay.
William Claiborne was the Secretary of State in the Virginia colony after 1626, and used his influence to partner with London-based capitalists to build a fur trading post in the upper Chesapeake Bay on Kent Island. The plan was to trade with the Susquahannocks and other tribes, competing with the Dutch and Swedes in New Amsterdam (New York) and Delaware. In addition, a plantation on the island was expected to provide food and other resources for trade with New England. (Robert Brenner, Merchants and revolution: commercial change, political conflict, and London's overseas traders, 1550-1653, Princeton University Press, 1993, p.121, http://books.google.com/books?id=amFQ3gq-SjQC (last checked March 4, 2013)
Claiborne knew, from George Calvert's visit to Jamestown in 1629, that a rival (and Catholic) colony could be created north of the Potomac River. Claiborne sailed from Jamestown back to London to lobby against the grant to the Calvert family. To bolster the claim that Kent Island was already settled, he sailed back across the Atlantic Ocean, built a plantation on Kent Island, and stocked the new plantation with a herd of cattle. Claiborne J. Mills Thornton III, "The Thrusting Out of Governor Harvey: A Seventeenth-Century Rebellion," The Virginia Magazine of History and Biography, Vol. 76, No. 1 (January 1968), p.21, http://www.jstor.org/stable/4247365 (last checked March 4, 2013)
Charles I issued Claiborne and his partners a license for trading in "corne, furs and any other commodities whatsoever." Claiborne never had a land grant for private ownership of Kent Island, but he did claim to have purchased the property from the Native Americans in 1631. The settlement sent a representative to the General Assembly that met in Jamestown in 1632.
J. Herbert Claiborne, "William Claiborne of Kent Island, The Virginia Magazine of History and Biography, Vol.1 No. 2 (April 1921), p.78-79, http://www.jstor.org/stable/1923023 (last checked March 4, 2013)

After Charles I signed the 1632 charter, the Virginia colonists maneuvered so the new Maryland colony would fail. Charles I's colonial governor in Virginia, John Harvey, wrote back to London that the Virginians "would rather knock their cattell on the heads then sell them to Maryland." (Letter from Governor Harvey to Secretary Windebank, December 16, 1634, in Colonial Papers Vol.VIII, No.37., Maryland State Archives, http://aomol.net/megafile/msa/speccol/sc2900/sc2908/000001/000003/html/am3--29.html (last checked March 4, 2013)
The 1632 grant to Lord Baltimore abolished Claiborne's claim to Kent Island, but he fought to retain control. Claiborne appealed to English officials in London, citing his occupation of the island prior to the grant. Claiborne also supported a political reaction in Virginia that "thrust out" colonial Governor William Harvey, forcing him to return to England in part because he would not oppose Charles I's grant to the Calverts.
The first Maryland colonists arrived on the Ark and Dove in 1634. The next year, supporters of Claiborne and Calvert fought a minor civil war in the Chesapeake Bay, after Marylanders seized one of Claiborne's trading vessels in the bay. Three Virginians died in the fighting.(John Thomas Scharf, History of Maryland From the Earliest Period to the Present Day, John B. Piet (Baltimore), 1879, p.109, http://books.google.com/books?id=CGU1AAAAIAAJ (last checked March 4, 2013)
Maryland established complete control over Kent Island in 1637, after Claiborne's creditors realized the fur trading had not been profitable. They sent a replacement for Claiborne and decided to accept Maryland's authority. In 1638, Claiborne's appeal to the Commissioners for the Plantations in London was rejected. In 1644, however, Claiborne re-seized his old fur trading post during an anti-Catholic uprising that was triggered by Virginians.
The Calverts regained control in 1646, but Claiborne once again stimulated another brief revolt in 1654 during the English Civil War. In the end, the Calvert's were reinstated as the leaders of the Maryland colony and Kent Island restored to aryland control. Claiborne made one last attempt in 1677. After Bacon's Rebellion, royal officials reviewed the conditions and role of colonial officials in Virginia. Claiborne was almost 90 years old, but still ambitious enough to lobby to have Kent Island restored to his control. J. Herbert Claiborne, "William Claiborne of Kent Island, The Virginia Magazine of History and Biography, p. 84-92
![]() in the 1632 charter for Maryland, the original boundary included a straight line across the Chesapeake Bay to Watkins' Point on the Eastern Shore, and then another straight line from Watkins’ Point due east to the ocean - but the border was altered in the 1877 Black-Jenkins award Map Source: US Fish and Wildlife Service, Wetlands Mapper |
If the charter for Maryland had not been revised to exclude the southern tip of the Delmarva Peninsula, then Maryland may have been granted control over not just the Potomac River, but also the entire bay. According to the 1632 charter for Maryland, "the southern boundary of the grant was composed of two straight lines... a line from Watkin's Point East to the Sea, and a line from the southern point of the mouth of the Potomac to Watkin's Point. The location of these lines depended simply upon the position of these two points."8


The 1632 charter defined the southern point of the mouth of the Potomac as "a certain Place, called Cinquack, situate near the mouth of the said River." Cinquack was an Algonquian town identified by John Smith on his map of Virginia. Though the town was located several miles south of the mouth of the Potomac River, Maryland accepted that its boundary started at Smith Point (at the lighthouse, after it was constructed) and never tried to claim territory south to the old location of Cinquack.
However, the Maryland-Virginia boundary on the eastern side of the Chesapeake Bay and on the Eastern Shore was not clear. The confusion became important after the area was settled by religious dissidents (primarily Quakers and Puritans) who had been expelled from Virginia in 1660. (After the Restoration of Charles II made clear that the Puritans had lost political control in England, Governor Berkeley "cleaned house" in Virginia.). The religious dissenters from Virginia who settled on the Eastern Shore of Maryland could avoid paying taxes to either colonial government if the boundary was not defined - and Edmund Scarborough, the Surveyor General of Virginia, was agressive in asserting Virginia's claims to land on the Eastern Shore above the 38th parallel.
In 1668 Philip Calvert of Maryland (uncle of the governor at the time, Charles Calvert) and Edmund Scarborough agreed to set the boundary along the 38th parallel, where the Potomac River empties into the Chesapeake Bay. The survey starts where the 38th parallel crosses the Pocomoke River, not at the edge of the Chesapeake Bay. As a result of starting at the Pocomoke River (perhaps to avoid a difficult traverse through marshland seen as having minimial value), the colonial officials in 1688 altered the 1632 charter boundaries. Using the main channel of the Pocomoke River to mark the colonial boundary between the eastern edge of the Chesapeake Bay and the 38th parallel gave Maryland some extra land, north and west of the Pocomoke River.

The Calvert-Scarborough line was surveyed with magnetic compasses, without correcting for the deviation from true north. A compass doesn't point to the North Pole; it points to magnetic north - a location NEAR, but not at, the geographic pole. After the boundary was accepted, it was realized that the line was about 5 degrees off from a true east-west slant. The line "tilts" to the northeast on the map today rather than runs due east. As a result, about 15,000 extra acres east of the Pocomoke River ended up in Virginia.9
A stickier problem was where the state line crossed the Chesapeake Bay and its various islands. Watkins Point, on the western edge of the Eastern Shore (that is, on the Chesapeake Bay side, not on the Atlantic Ocean) had been named as the dividing line in the 1632 Maryland charter. The charter also referenced the river Wighco (or Wigloo), based on Johh Smith's 1624 map. However, Virginia claimed that the exact location of Watkins Point referenced in the original Maryland charter was unclear by the 1850's.
In the 1850's, the two states started to resolve the issue. At the request of Virginia and Maryland, in 1858 Lieutenant Michler of the United States Topographical Engineers mapped the shorelines of the Eastern Shore and Chesapeake Bay islands (plus the location of the Fairfax Stone at the headwaters of the Potomac River. Michler's survey mapped the area, but determining where to draw the boundary line was a political rather than a surveying decision.
Though the states agreed that the Wigloo (or Wighco) mentioned in the charter was the Pocomoke River, Virginians wanted to harvest oysters in all of Pocomoke Bay and argued that "Watkins Point" was actually the mpouth of the Annamessex River further north - despite all the historic maps showing that the southwestern tip of a Somerset County peninsula still called Watkins Point was the reference point in the charter.






The 1877 Black and Jenkins arbitration affirmed the locally-accepted boundaries on Smith's Island (one of the Russell Isles on John Smith's map) between Horse Hammock-Sassafrass Hammock. Through that 1877 arbitration and a series of later adjustments, odd twists and turns in the Maryland-Virginia boundary throughout the Chesapeake Bay granted rights for Virginians to harvest the valuable fish and oyster resources of "Smith's Island, all of Fox Island, the great oyster rock known as Muddy Marsh in Tangier Sound, and the valuable crabbing flats from Green Harbor Island to Robin Hood Bar in Pocomoke Sound."11
After the Civil War, Maryland and Virginia disagreed on how to manage the oysters in the Chesapeake Bay. Maryland did not allow dredging, but Virginia permitted boats to scrape the bottom of the bay and disrupt the natural habitat. "Pirates" were accused of harvesting illegally on either side of the border.
Both states supported their separate rules (and watermen) by establishing state navies on the Chesapeake Bay. In 1882-83, Virginia's governor personally led two expeditions to capture oyster pirates at the mouth of the Rappahannock River.
In Virginia, a Board of the Chesapeake kept the Tangier and Pocomoke schooners , plus the Chesapeake and Accomac steamers on the bay, theoretically to protect Virginia watermen from the equivalent forces from shoot-outs between Maryland and Virginia fishermen. The Fisheries Commission inherited the responsibility in 1897, and added two other steamers, the Commodore Maury and James River. The Fisheries Commissioin was renamed the Marine Resources Commission in 1968.12
Disputes about which state could enforce varying rules about dredging oysters, etc., continued through the 1850's, until the adoption of another Maryland-Virginia Compact in 1958 (at Mount Vernon, again). That 1958 agreement superceded the arrangements made in the 1785 compact.
Virginia and Maryland keep debating the 1632 boundary dispute and how the Compact of 1785 limits Maryland's control over the bottom of the Potomac River. A 1958 Maryland-Virginia Compact replaced the Compact of 1785 in hopes of resolving disputed claims to oyster beds and fishery resources - but lawsuits continue to cite colonial-era documents, as well as the 1958 agreement.
In 1997, Maryland claimed that the Fairfax County Water Authority needed a Maryland state permit, in order to extend a water pipe to the middle of the Potomac River. Fairfax wanted to minimize the sediment in the water that it will treat at its Corbalis Water Treatment plant, near the Loudoun County line, by extracting raw water from the middle of the river. The old Fairfax County intake pipe on the southern shoreline was receiving water with too much sediment, partly due to muddy runoff from housing developments in Loudoun County. Fairfax wanted to suck cleaner water from the middle of the river. The water in the middle of the Potomac River is cleaner, in large part because C&O Canal National Historical Park on the Maryland side provides a buffer of natural vegetation and there is less mud flowing into the Potomac on the north bank.
That proposal created yet one more Virginia v. Maryland lawsuit in front of the US Supreme Court. Maryland opposed the plans of the Fairfax County Water Authority (now Fairfax Water), and tried to force the Virginia county to get a Maryland state permit before constructing the intake pipe on the bed of the Maryland river. Part of the "back story" is that Maryland wanted Virginia to reduce the impacts of shoreline development that pollute the Potomac River. Simply avoiding those impacts by extending the intake pipe addressed the sympton without dealing with the cause.
In 2003, the US Supreme Court ruled that Fairfax County has the right to place the intake pipe on Maryland's river bed without having to obtain a permit from Maryland. Maryland owns the whole river, due to the wording in the 1634 charter, but various bi-state negotiations and court decisions (especially the 1877 Black-Jenkins Award) have made it possible for Virginia to use the Potomac River.
In 2011, landowners in Maryland claimed control over the riverbank downstream of Harpers Ferry, on the Virginia side of the Potomac River. Maryland sold rights to the bottom of the river until 1862, and the parcel in dispute has been private property since 1833.13


Potomac Shores, Inc. asserted that their property boundaries remained intact, even though the river had shifted and thus the edge of the river had moved. If the median high-water mark in the 1830's defined ownership, then river rafters who floated downstream past Harpers Ferry were trespassing on Maryland property, when getting back on dry land at Potomac Wayside.
Outfitters supporting rafting trips had permits to cross the property from the National Park Service. The Maryland landowners claimed ownership between the low-water mark and the median high-water mark, but the Federal agency was not a party to the lawsuit. Judge Long of the Washington County Circuit Court of Maryland ruled in 2013 that the Black-Jenkins award had settled the issue:14

NOTE: Virginia does not "own" any of the Potomac River below the low-water mark, but Maryland does not own all of the river either. The District of Columbia actually owns some of the Potomac River. A portion of the river between Jones Point and Chain Bridge was once part of Maryland, but was incorporated within the boundaries of the District of Columbia when it was established. Maryland's rights to the Potomac transferred at that time to the District, and the Boundary Channel near the Pentagon is owned by DC. (After West Virginia was established in 1863, Maryland retained its claims to the entire river, from Harpers Ferry up to the Fairfax Stone. West Virginia stops at the shoreline, and does not extend into the middle of the Potomac River.)

