 in modern Stafford County
Source: Maryland State Archives, Nova Terrae-Mariae tabula (by Jerome Hawley and John Lewger, 1635)
Maryland maps still laid claim to Northern Virginia as late as 1671, showing Potomac Creek as the boundary
Source: Columbus State University Archives, Noua Terrae-Mariae Tabula, or Lord Baltimore's Map, 1635. Second edition by John Ogilby, 1671
Augustine Herrman, a Dutch merchant not dependent upon the Calverts, prepared a map in 1670 that depicted the accurate status of the Potomac River and Potomac Creek
Source: Library of Congress, Virginia and Maryland as it is planted and inhabited this present year 1670 (by Augustine Herrman)
the French in 1718 defined the Acconachena [Shenandoah] River as the Maryland-Virginia border
Source: Library of Congress, Carte de la Louisiane et du cours du Mississippi... (by Guillaume de L'Isle, 1718)
in 1721, John Senex duplicated Guillaume de L'Isle in using the Acconachena [Shenandoah] River as the Maryland-Virginia border
Source: Library of Congress, A Map of Louisiana and of the River Mississippi (by John Senex, 1721)
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 Pocomoke 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).
Maryland manages oyster bars in the Potomac River, up to the boundary line with Virginia
Source: Maryland Department of Natural Resources, Maryland's Historic Oyster Bars
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 river bottom 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. Virginia landowners chose to interpret the right of "navigation and use" 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.
In 1688, Thomas, Lord Culpeper arranged to have King James II re-confirm the Northern Neck grant that Charles II had originally issued in 1649. By that time, Culpeper owned 5/6ths of what later became known as the Fairfax Grant. In his 1688 action, King James II used language that reversed ownership of the Potomac River by giving away (emphasis added):7
There was apparently no legalistic examination of language regarding the exact ownership of the shoreline in the 17th or 18th Century. 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 catching "their" fish or using the land between the high-water and low-water marks.8
George Washington's fishery was at the mouth of Dogue Creek, downstream from the Mount Vernon mansion house
Map Source: Library of Congress, A map of General Washington's farm of Mount Vernon from a drawing transmitted by the General
modern boundaries at the location of George Washington's fishery, near Ferry Point
Map Source: US Geological Survey (USGS), Mount Vernon 7.5 x 7.5 topographic map (2011)
Virginia's first constitution, adopted in 1776, sought to increase colonial unity by dropping Virginia's claims to lands within the chartered boundaries of Maryland. The Virginia constitution used language that did not clarify if the state still claimed ownership of the shoreline of the Potomac River down to the low-water mark:9
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 support 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.
Virginia owns both Cape Charles and Cape Henry, so it controls the mouth of the Chesapeake Bay
Source: National Atlas
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.
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:10
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:11
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