Virginia reached its greatest extent in 1609, when King James I issued a second charter to the Virginia Company of London that defined new boundaries for the Virginia colony. The new claims extended north to what is now Maine, south to near the modern North-South Carolina border, and "from sea to sea, west and northwest" all the way to the Pacific Ocean.
Virginia's claims to the Northwest Territory were based on that charter, plus military conquest of Kaskaskia and Vincennes during the American Revolution. Those claims were upheld by colonial and then state officials until 1783.
A third charter issued by King James I in 1612 retained Virginia's rights to "all that Space and Circuit of Land lying from the Sea Coast of the Precinct aforesaid, up into the Land throughout from Sea to Sea West and North-west," plus it expanded the colony's boundaries eastward to include the recently-discovered island of Bermuda.
Virginia has been reduced in size in various ways since 1612. The Virginia Company spun off Bermuda in 1615, when the Bermuda Company obtained a separate charter from King James I for the Plantation of the Somers Isles.1
In 1624, after the Virginia Company had failed to produce a profit and the 1622 uprising demonstrated the company's inability to even defend the colony, King James I revoked the 1612 charter. The conversion of Virginia from a private business into a royal colony altered the basis for government, but the king did not alter any of Virginia's boundaries in 1624.
Despite subsequent legal confusion over the validity of outdated charters - and perhaps in part because of it - Virginia officials have cited the boundaries in the 1609 charter whenever there was an opportunity to assert control over western lands that are today part of western Pennsylvania, Ohio, Indiana, Illinois, Michigan, and Wisconsin.
What the king granted to a few well-connected friends in the Virginia Company, the king could take away. The boundaries of the colony were modified by various actions of the king, from the creation of Maryland in 1632 through the Quebec Act of 1774.
Once Virginia became an independent state, its western boundary was minimized first by a 1781 voluntary land cession of the territory past the Ohio River to the Confederation Congress. That was followed by creation of the State of Kentucky in 1792, then the splitting off of West Virginia during the 1861-65 Civil War. In 1866 the US Congress declared that Berkeley and Jefferson counties were part of West Virginia, and in 1870 the US Supreme Court ruled that action was valid.
On the eastern boundary, Virginia's claim to the seabed of the Atlantic Ocean was eliminated by a 1947 Supreme Court decision, though the US Congress restored rights to the first three miles of the Outer Continental Shelf in the 1953 Submerged Lands Act.
Virginia's Illinois County was created in 1778, based on the conquest by George Rogers Clark and citing claims dating back to the 1609 charter, but that land was ceded to the new United States in 1783 and become the Northwest Territory when the US Congress accepted the land cession in 1784
Map Source: ESRI, ArcGIS Online
boundaries of Virginia in 1784, after ceding northwestern land claims to the national government but before the creation of Kentucky (1792) or West Virginia (1863)
When English kings created other colonies such as Maryland and Carolina, they changed the northern and southern boundaries of Virginia. Grants to other colonies included overlapping claims to western lands. The western edge of Virginia remained unclear when King George III issued the Proclamation of 1763. That proclamation settlement in the Mississippi River watershed, where the French had relinquished their claims in the 1763 Treaty of Paris that ended the Seven Years War.
The western edge of authorized settlement was moved through negotiations with the Cherokee (1768 Treaty of Hard Labor, followed by the 1770 Treaty of Lochaber in 1770) and the Iroquois (1768 Treaty of Fort Stanwix). Those treaties opened most of the desirable land in the Ohio River watershed for colonial settlement, though Shawnee and other nations disputed the authority of the Cherokee and Iroquois to permit colonial settlement there.
England's tacit acceptance of Virginia's western land claims ended with the 1774 Quebec Act. It transferred responsibility for granting ownership for most lands west of the Appalachian Mountains from the restless colonies such as Virginia, Maryland, Pennsylvania, and New York to the more-loyal province of Quebec.
the Proclamation of 1763 attempted to create an Indian Reserve and block colonial settlement on lands west of the Allegheny Mountains (shaded green), limiting Virginia's ability to issue legal title to lands granted to the Loyal Land Company, the Ohio Land Company, and others
Source: Library of Congress, A New map of North America from the latest discoveries (1763)
During the fifth of the Virginia "conventions" held after the colonial government collapsed and before the General Assembly was created, Virginia leaders declared independence. In the first Virginia constitution adopted by that convention in June, 1776, the new Commonwealth of Virginia blatantly ignored King George III's transfer of western lands to Quebec, a colony which stayed loyal to King George III during the American Revolution.
The Virginians were more accommodating to those other 12 colonies who joined the fight against Great Britain. In June, 1776, the Fifth Convention adopted a constitution that defined the new state's boundaries as:2
In addition to Virginia, other colonies were constrained by the Proclamation of 1763. Thomas Jefferson listed a specific complaint about the Quebec Act in the Declaration of Independence, when he justified the 13 colony's break from King George III:3
After declaring independence, Virginia asserted in its first constitution that the state boundaries included the vast territory west of Pennsylvania/New York and north of the 36° 30' parallel (the border with North Carolina).
In 1778, Virginia troops led by George Rogers Clark captured British encampments at Kaskaskia and Vincennes in the Illinois territory. The Virginia General Assembly then created Ilinois County, encompassing all the lands west of the Ohio River.
Military conquest of the northwest, extending to the Mississippi River, added a key element to Virginia's claim over the land. King George III had tried to define western boundaries for the colonies in the Quebec Act, and Virginia troops alone had been responsible for defeating the king's claim. As viewed in Virginia, what the king lost... Virginia gained.
Virginia's control over the territory between the Ohio River and the Great Lakes generated conflicts between states with competing land claims, and with states that had no such claims. If Virginia was allowed to sell its western lands and pocket the revenue, plus control elections and administer the area, then the other states would see Virginia's economic and political power grow at their expense. Whatever the reasons in the different colonies for declaring independence, in no case did the other 12 states relish the prospect of replacing domination from England with domination from Virginia.
A "congress" of the colonies started meeting formally in 1774. The rebellious colonies/states started fighting the American Revolution together starting in 1775. Virginia had been the first state to ratify the proposed Articles on Confederation in 1777. Maryland, Delaware and New Jersey delayed, demanding that states with western land claims relinquish them before creating a new national union.
Over half of the states participating in the Continental Congress (MA, CT, NY, VA, NC, SC, and GA) had charters with no fixed boundary on their western edge, or cited other authorities to justify overlapping claims to the some of the same territory claimed by Virginia.
The other six states (NH, RI, NJ, PA, DE, and MD) had no justification to assert authority over western lands, but still had great interest regarding how that land would be sold, settled, and administered. Those six states feared that in the future, as population grew, the landlocked states would lose power and influence as the other states expanded.
The ultimate solution was to have the all the states establish a clear territorial line on their western borders, to give land claims west of those borders to the new national government, and to create new states from that public domain. That solution limited the future growth of the seven states with land claims, while income from land sales in the new national territory could be used to pay off the national government's debts from the Revolutionary War. The new public domain also provided a way for the Congress to honor land grants promised as bounties for serving in the Continental Army.
George Rogers Clark captured Kaskaskia and Vincennes during the American Revolution, cementing Virginia's claims to the territory northwest of the Ohio River
Source: National Park Service, Fort Jefferson, 1780-1781: A Summary Of Its History
Virginia's land borders were modified between the 1632 creation of Maryland (yellow) and the 1870 Supreme Court ruling that Berkeley and Jefferson counties (red) were legally added to West Virginia by Congressional action in 1866
Source: Franklin K. Van Zandt, Boundaries of the United States and the Several States, Geological Survey Professional Paper 909 (p.144)
Legislators in the General Assembly knew that most trade in the region would be via boats going down the Ohio and Mississippi rivers to New Orleans, rather than to Virginia's ports on the Chesapeake Bay. Virginia's leaders were willing to transfer the state's claims to the national government, and did not plan to retain political control permanently over lands northwest of the Ohio River.
Affirming the claims of Maryland/Pennsylvania to the boundaries defined in charters to Calvert and Penn, plus agreeing to create new states from lands northwest of the Ohio River, would reduce interstate conflicts. Though it had been hard to capture Kaskaskia and Vincennes, it would be even harder to govern them from Richmond.
Congress encouraged Virginia's land cessions. Creating a public domain, a vast stretch of land controlled by a united national government rather than having separate states retain control over lands stretching to the Mississippi River, would tighten the bonds between Virginia and the other 12 breakaway colonies and would focus colonial efforts on winning independence from Great Britain.
Arranging the land cession involved complicated politics. After Delaware ratified the Articles of Confederation on February 1, 1779, Maryland was left as the last holdout.4
Virginia reacted to the delay by opening a land office in 1779. It started to sell western lands to raise revenue, and issued patents for land based on old military warrants issued for service in the French and Indian War.
In response, the Continental Congress called for all states to freeze their land sales:5
Virginia's General Assembly objected strongly to interference by the nascent national government in the independent state's internal affairs. The legislature issued a "remonstrance" on December 14, 1779:6
Maryland's resistance postponed adoption of the Articles of Confederation for three years.
New York led the land cession process by example on January 17, 1780. It abandoned its flimsy claim that treaties with the Six Nations had conveyed the land claims of the Iroquois, obtained by right of conquest, to territory southwest of Lake Ontario. New York authorized its delegates to the Continental Congress to transfer the state's rights (if any...) to lands outside of its established boundaries.
Congress then finessed the issue over national vs. state authority by simply asking the other states to mimic New York.
Virginia's legislature relinquished its land claims on January 2, 1781. It imposed conditions that required the Congress to:7
Those conditions would validate property ownership of Virginia speculators, but eliminate the potential value of various land companies chartered outside of Virginia. In particular, those conditions blocked land claims of the Transylvania colony proposed by Judge Richard Henderson, and ensured Virginia's claim of authority over Kentucky.
Virginia included in its January 2, 1781 action that:8
Maryland finally signed the Articles of Confederation on March 1, 1781, and the 13 colonies officially became one nation.
A spur for Maryland's action was a series of raids by the British navy and privateers throughout the Chesapeake region in 1780. When Maryland asked the French to provide ships to block the raids, the French responded with a suggestion that Maryland should first ratify the Articles of Confederation. It did so slightly more than six months before Lord Cornwallis surrendered at Yorktown.
Virginia renewed its cession offer on October 20, 1783, without requiring a guarantee of the state borders. That finessed the previous requirement that the other states acknowledge Virginia's authority over Kentucky. Congress accepted Virginia's new cession offer on March 1, 1784.9
Massachusetts and Connecticut, like Virginia, had charters that established land claims extending into the Ohio Country
Source: Bureau of Land Management, A History of the Rectangular Survey System
A remaining complication: the Congress chose rejected the Virginia conditions, as established on January 2, 1781. Virginia's land cessions were not accepted immediately. The treaty of Paris between the United States and England in 1783 established the Mississippi River as the western edge of the new nation, but debate regarding state land claims west of the Ohio River continued until 1784.
In the two years of further discussion, the other states sought to gain control of the Virginia lands between the Proclamation Line of 1763 and the Ohio River. Only one succeeded; Connecticut managed to obtain rights to a "Western Reserve" in what is now Ohio.
In March 1784, Thomas Jefferson wrote to George Washington on the urgency of Virginia improving its transportation network westward from the Potomac River to the Ohio River, so Virginia rather than New York would capture the future trade between the "Northwest" and ports on the Atlantic coast. In that letter, he justified why Virginia should retain western lands to the Ohio River, especially the Kanwaha River watershed, but allow new states to be formed from lands beyond the Ohio River:10
Virginians played a major role in shaping the management of the new Northwest Territory. Through the Land Ordinance of 1785, Thomas Jefferson proposed the system by which lands would be surveyed before sale, using what evolved into the Public Land Survey System. He would play an even greater role in acquiring Federal territory west of the Mississippi River, through the Louisiana Purchase.
The Northwest Land Ordinance of 1785 defined how the new public domain of the national government would be sold, and protected one remaining claim of Virginia to lands northwest of the Ohio River. Virginia had set aside lands in Kentucky for soldiers and sailors who had served in the state or national forces during the American Revolution - one incentive to enlist or remain in the military was the potential value of the land grants. Virginia was concerned that the designated Kentucky lands on the Cumberland River, between the Green and Tennesse, would not be sufficient to redeem all bounties issued for enlisting.
Just in case, Virginia's cession to the Congress identified a 4.2 million acre Virginia Military Reserve in Ohio, where those who had served in Virginia's military forces during the American Revolution (and those who had purchased the land rights from the soldiers and officers...) could claim their property:11
one of the first maps issued after the end of the American Revolution finessed the western boundaries of Virginia and Pennsylvania by omitting them completely
Source: Library of Congress, The United States according to the definitive treaty of peace signed at Paris Sept. 3d. 1783 (William McMurray, 1784)