Northern Neck Proprietary

The unsettled portions of his domain were finally confiscated during the American Revolution by the Virginia Act of 1779 and when he died in 1781 the Proprietary effectively ceased to exist.

A portion of this estate, however, was later the subject of the landmark Supreme Court case Martin v. Hunter's Lessee (1816).

In September 1649, King Charles II of England granted to seven Englishmen all of Virginia between the Rappahannock and Potomac Rivers as a Proprietary.

The proprietors thought little of their grant since Charles II, due to political struggles in England, was a king without a kingdom.

Because he was only sixteen years old at the time, the affairs of the Proprietary fell to his mother, Lady Catherine Fairfax.

Before leaving, he rode over much of his domain, and set aside for himself a tract of 12,588 acres (50.94 km2) near Great Falls, in what was to become Fairfax County.

[4] Prior to 1649, the entire Northern Neck had been designated by the Assembly as one large county called Northumberland.

This was to be the work of Colonel Peter Jefferson and Thomas Lewis — the "Fairfax Line" party — in 1746 and 1747, which finally settled the disputed claims.

[12] The Fairfax grant extended westward to the boundary with the colony (later state) of Maryland, although much of the western land was unoccupied by colonists at the time.

In 1746 surveyors led by Colonel Peter Jefferson (Thomas Jefferson's father) and Thomas Lewis placed the "Fairfax Stone" at the source of the Potomac River, then made an approximately 77-mile line of demarcation known as the "Fairfax Line", extending south-eastward from that Stone to the source of the Rappahannock River.

[13] Because the Potomac River initially runs westward from its source, and the state of West Virginia was created during American Civil War, it now marks the junction of Tucker, Grant and Preston Counties and is in Fairfax Stone Historical Monument State Park.